{"No generic method 'Average' on type 'System.Linq.Enumerable' is compatible with the supplied type arguments and arguments. No type arguments should be provided if the method is non-generic. "}

[System.InvalidOperationException]: {"No generic method 'Average' on type 'System.Linq.Enumerable' is compatible with the supplied type arguments and arguments. No type arguments should be provided if the method is non-generic. "}

Data: {System.Collections.ListDictionaryInternal}

HelpLink: null

InnerException: null

Message: "No generic method 'Average' on type 'System.Linq.Enumerable' is compatible with the supplied type arguments and arguments. No type arguments should be provided if the method is non-generic. "

Source: "System.Core"

StackTrace: " at System.Linq.Expressions.Expression.FindMethod(Type type, String methodName, Type[] typeArgs, Expression[] args, BindingFlags flags)\r\n at System.Linq.Expressions.Expression.Call(Type type, String methodName, Type[] typeArguments, Expression[] arguments)\r\n at Telerik.Windows.Data.Expressions.EnumerableSelectorAggregateFunctionExpressionBuilder.CreateMethodCallExpression(LambdaExpression memberSelectorExpression) in c:\\Builds\\WPF_Scrum\\Release_WPF\\Sources\\Development\\Core\\Data\\Expressions\\Grouping\\Aggregates\\EnumerableSelectorAggregateFunctionExpressionBuilder.cs:line 48\r\n at Telerik.Windows.Data.Expressions.EnumerableSelectorAggregateFunctionExpressionBuilder.CreateAggregateExpression() in c:\\Builds\\WPF_Scrum\\Release_WPF\\Sources\\Development\\Core\\Data\\Expressions\\Grouping\\Aggregates\\EnumerableSelectorAggregateFunctionExpressionBuilder.cs:line 30\r\n at Telerik.Windows.Data.EnumerableSelectorAggregateFunction.CreateAggregateExpression(Expression enumerable

Expression) in c:\\Builds\\WPF_Scrum\\Release_WPF\\Sources\\Development\\Core\\Data\\Data\\Grouping\\Aggregates\\EnumerableSelectorAggregateFunction.cs:line 76\r\n at Telerik.Windows.Data.Expressions.GroupDescriptorExpressionBuilder.<ProjectionPropertyValueExpressions>b__3(AggregateFunction f) in c:\\Builds\\WPF_Scrum\\Release_WPF\\Sources\\Development\\Core\\Data\\Expressions\\Grouping\\GroupDescriptorExpressionBuilder.cs:line 288\r\n at System.Linq.Enumerable.WhereSelectEnumerableIterator`2.MoveNext()\r\n at System.Collections.Generic.List`1..ctor(IEnumerable`1 collection)\r\n at System.Linq.Enumerable.ToList[TSource](IEnumerable`1 source)\r\n at Telerik.Windows.Data.Expressions.GroupDescriptorExpressionBuilder.CreateProjectionInitExpression() in c:\\Builds\\WPF_Scrum\\Release_WPF\\Sources\\Development\\Core\\Data\\Expressions\\Grouping\\GroupDescriptorExpressionBuilder.cs:line 279\r\n at Telerik.Windows.Data.Expressions.GroupDescriptorExpressionBuilder.CreateAggregateFunctionsProjectionMemberBin

ding() in c:\\Builds\\WPF_Scrum\\Release_WPF\\Sources\\Development\\Core\\Data\\Expressions\\Grouping\\GroupDescriptorExpressionBuilder.cs:line 272\r\n at Telerik.Windows.Data.Expressions.GroupDescriptorExpressionBuilder.<CreateMemberBindings>d__0.MoveNext() in c:\\Builds\\WPF_Scrum\\Release_WPF\\Sources\\Development\\Core\\Data\\Expressions\\Grouping\\GroupDescriptorExpressionBuilder.cs:line 173\r\n at System.Collections.Generic.List`1..ctor(IEnumerable`1 collection)\r\n at System.Dynamic.Utils.CollectionExtensions.ToReadOnly[T](IEnumerable`1 enumerable)\r\n at System.Linq.Expressions.Expression.MemberInit(NewExpression newExpression, IEnumerable`1 bindings)\r\n at Telerik.Windows.Data.Expressions.GroupDescriptorExpressionBuilder.CreateSelectBodyExpression() in c:\\Builds\\WPF_Scrum\\Release_WPF\\Sources\\Development\\Core\\Data\\Expressions\\Grouping\\GroupDescriptorExpressionBuilder.cs:line 161\r\n at Telerik.Windows.Data.Expressions.GroupDescriptorExpressionBuilder.CreateResultSelectorExpressio

n() in c:\\Builds\\WPF_Scrum\\Release_WPF\\Sources\\Development\\Core\\Data\\Expressions\\Grouping\\GroupDescriptorExpressionBuilder.cs:line 153\r\n at Telerik.Windows.Data.Expressions.GroupDescriptorExpressionBuilder.get_ResultSelectorExpression() in c:\\Builds\\WPF_Scrum\\Release_WPF\\Sources\\Development\\Core\\Data\\Expressions\\Grouping\\GroupDescriptorExpressionBuilder.cs:line 109\r\n at Telerik.Windows.Data.Expressions.GroupDescriptorExpressionBuilderBase.CreateQuery() in c:\\Builds\\WPF_Scrum\\Release_WPF\\Sources\\Development\\Core\\Data\\Expressions\\Grouping\\GroupDescriptorExpressionBuilderBase.cs:line 18\r\n at Telerik.Windows.Data.Expressions.GroupDescriptorCollectionExpressionBuilder.CreateQuery() in c:\\Builds\\WPF_Scrum\\Release_WPF\\Sources\\Development\\Core\\Data\\Expressions\\Grouping\\GroupDescriptorCollectionExpressionBuilder.cs:line 28\r\n at Telerik.Windows.Data.QueryableExtensions.GroupBy(IQueryable source, IEnumerable`1 groupDescriptors) in c:\\Builds\\WPF_Scrum\\Release_WPF\

\Sources\\Development\\Core\\Data\\Collections\\QueryableExtensions.cs:line 184\r\n at Telerik.Windows.Data.QueryableCollectionView.CreateView() in c:\\Builds\\WPF_Scrum\\Release_WPF\\Sources\\Development\\Core\\Data\\Collections\\QueryableCollectionView.cs:line 480\r\n at Telerik.Windows.Data.QueryableCollectionView.get_QueryableView() in c:\\Builds\\WPF_Scrum\\Release_WPF\\Sources\\Development\\Core\\Data\\Collections\\QueryableCollectionView.cs:line 511\r\n at Telerik.Windows.Data.QueryableCollectionView.CreateInternalList() in c:\\Builds\\WPF_Scrum\\Release_WPF\\Sources\\Development\\Core\\Data\\Collections\\QueryableCollectionView.cs:line 575\r\n at Telerik.Windows.Data.QueryableCollectionView.EnsureInternalList() in c:\\Builds\\WPF_Scrum\\Release_WPF\\Sources\\Development\\Core\\Data\\Collections\\QueryableCollectionView.cs:line 563\r\n at Telerik.Windows.Data.QueryableCollectionView.get_InternalList() in c:\\Builds\\WPF_Scrum\\Release_WPF\\Sources\\Development\\Core\\Data\\Collections\\Queryab

leCollectionView.cs:line 554\r\n at Telerik.Windows.Data.QueryableCollectionView.GroupedIndexOf(Object item) in c:\\Builds\\WPF_Scrum\\Release_WPF\\Sources\\Development\\Core\\Data\\Collections\\QueryableCollectionView.cs:line 1499\r\n at Telerik.Windows.Data.QueryableCollectionView.InternalIndexOf(Object item) in c:\\Builds\\WPF_Scrum\\Release_WPF\\Sources\\Development\\Core\\Data\\Collections\\QueryableCollectionView.cs:line 1491\r\n at Telerik.Windows.Data.QueryableCollectionView.TryRestorePreviousCurrency() in c:\\Builds\\WPF_Scrum\\Release_WPF\\Sources\\Development\\Core\\Data\\Collections\\QueryableCollectionView.cs:line 847\r\n at Telerik.Windows.Data.QueryableCollectionView.InitializeCurrencyOnRefresh() in c:\\Builds\\WPF_Scrum\\Release_WPF\\Sources\\Development\\Core\\Data\\Collections\\QueryableCollectionView.cs:line 843\r\n at Telerik.Windows.Data.QueryableCollectionView.RefreshOverride() in c:\\Builds\\WPF_Scrum\\Release_WPF\\Sources\\Development\\Core\\Data\\Collections\\QueryableCollect

ionView.cs:line 824\r\n at Telerik.Windows.Data.QueryableCollectionView.RefreshInternal() in c:\\Builds\\WPF_Scrum\\Release_WPF\\Sources\\Development\\Core\\Data\\Collections\\QueryableCollectionView.cs:line 772\r\n at Telerik.Windows.Data.QueryableCollectionView.RefreshOrDefer() in c:\\Builds\\WPF_Scrum\\Release_WPF\\Sources\\Development\\Core\\Data\\Collections\\QueryableCollectionView.cs:line 767\r\n at Telerik.Windows.Data.QueryableCollectionView.InvalidatePagingAndRefresh() in c:\\Builds\\WPF_Scrum\\Release_WPF\\Sources\\Development\\Core\\Data\\Collections\\QueryableCollectionView.cs:line 393\r\n at Telerik.Windows.Data.QueryableCollectionView.OnGroupDescriptorsCollectionChanged(Object sender, NotifyCollectionChangedEventArgs e) in c:\\Builds\\WPF_Scrum\\Release_WPF\\Sources\\Development\\Core\\Data\\Collections\\QueryableCollectionView.cs:line 416\r\n at System.Collections.ObjectModel.ObservableCollection`1.OnCollectionChanged(NotifyCollectionChangedEventArgs e)\r\n at Telerik.Windows.Data.R

adObservableCollection`1.OnCollectionChanged(NotifyCollectionChangedEventArgs e) in c:\\Builds\\WPF_Scrum\\Release_WPF\\Sources\\Development\\Core\\Data\\Collections\\RadObservableCollection.cs:line 143\r\n at Telerik.Windows.Data.ObservableItemCollection`1.OnCollectionChanged(NotifyCollectionChangedEventArgs e) in c:\\Builds\\WPF_Scrum\\Release_WPF\\Sources\\Development\\Core\\Data\\Collections\\ObservableItemCollection.cs:line 93\r\n at Telerik.Windows.Data.RadObservableCollection`1.InsertItem(Int32 index, T item) in c:\\Builds\\WPF_Scrum\\Release_WPF\\Sources\\Development\\Core\\Data\\Collections\\RadObservableCollection.cs:line 190\r\n at Telerik.Windows.Controls.Charting.DataBindingHelper.PerformSampling(QueryableCollectionView dataEngine, Int32 samplingThreshold, IEnumerable`1 samplingFunctions) in c:\\Builds\\WPF_Scrum\\Release_WPF\\Sources\\Development\\Controls\\Chart\\Chart\\Data\\DataBindingHelper.cs:line 759\r\n at Telerik.Windows.Controls.Charting.DataBindingHelper.ProcessNoGrouping(Series

Mapping seriesMapping, QueryableCollectionView dataEngine, Int32 samplingThreshold, ZoomScrollSettings zoomScrollSettings, ISeriesDefinition defaultSeriesDefinition, AxisRangeState axisXRangeState) in c:\\Builds\\WPF_Scrum\\Release_WPF\\Sources\\Development\\Controls\\Chart\\Chart\\Data\\DataBindingHelper.cs:line 460\r\n at Telerik.Windows.Controls.Charting.DataBindingHelper.ProcessMapping(SeriesMapping seriesMapping, QueryableCollectionView dataEngine, Int32 samplingThreshold, ZoomScrollSettings zoomScrollSettings, ISeriesDefinition defaultSeriesDefinition, AxisRangeState axisXRangeState) in c:\\Builds\\WPF_Scrum\\Release_WPF\\Sources\\Development\\Controls\\Chart\\Chart\\Data\\DataBindingHelper.cs:line 271\r\n at Telerik.Windows.Controls.Charting.DataBindingHelper.ProcessMappings(SeriesMappingCollection seriesMappings, QueryableCollectionView dataEngine, Int32 samplingThreshold, ZoomScrollSettings zoomScrollSettings, ISeriesDefinition defaultSeriesDefinition, AxisRangeState axisXRangeState) in c:\\Builds

\\WPF_Scrum\\Release_WPF\\Sources\\Development\\Controls\\Chart\\Chart\\Data\\DataBindingHelper.cs:line 245\r\n at Telerik.Windows.Controls.Charting.DataBindingHelper.GenerateDataSeries(Object originalData, SeriesMappingCollection seriesMappings, ISeriesDefinition defaultSeriesDefinition, ChartFilterDescriptorCollection globalFilterDescriptors, ChartSortDescriptorCollection globalSortDescriptors, SamplingSettings samplingSettings, ZoomScrollSettings zoomScrollSettings, AxisRangeState axisXRangeState) in c:\\Builds\\WPF_Scrum\\Release_WPF\\Sources\\Development\\Controls\\Chart\\Chart\\Data\\DataBindingHelper.cs:line 48\r\n at Telerik.Windows.Controls.RadChart.GenerateDataSeries(Object originalData, SeriesMappingCollection seriesMappings, ChartArea chartArea) in c:\\Builds\\WPF_Scrum\\Release_WPF\\Sources\\Development\\Controls\\Chart\\Chart\\RadChart.cs:line 1288\r\n at Telerik.Windows.Controls.RadChart.GenerateDataSeries(Object originalData) in c:\\Builds\\WPF_Scrum\\Release_WPF\\Sources\\Development\\Co

ntrols\\Chart\\Chart\\RadChart.cs:line 1269\r\n at Telerik.Windows.Controls.RadChart.Rebind(Object originalData) in c:\\Builds\\WPF_Scrum\\Release_WPF\\Sources\\Development\\Controls\\Chart\\Chart\\RadChart.cs:line 894\r\n at Telerik.Windows.Controls.RadChart.Rebind() in c:\\Builds\\WPF_Scrum\\Release_WPF\\Sources\\Development\\Controls\\Chart\\Chart\\RadChart.cs:line 790\r\n at Telerik.Windows.Controls.Charting.SeriesMapping.RebindChart() in c:\\Builds\\WPF_Scrum\\Release_WPF\\Sources\\Development\\Controls\\Chart\\Chart\\Data\\SeriesMapping.cs:line 375\r\n at Telerik.Windows.Controls.Charting.SeriesMapping.ManageChangeNotifications(Object originalData, Object oldData) in c:\\Builds\\WPF_Scrum\\Release_WPF\\Sources\\Development\\Controls\\Chart\\Chart\\Data\\SeriesMapping.cs:line 354\r\n at Telerik.Windows.Controls.Charting.SeriesMapping.ItemsSourcePropertyChanged(DependencyObject target, DependencyPropertyChangedEventArgs args) in c:\\Builds\\WPF_Scrum\\Release_WPF\\Sources\\Development\\Controls\\

Chart\\Chart\\Data\\SeriesMapping.cs:line 331\r\n at System.Windows.DependencyObject.OnPropertyChanged(DependencyPropertyChangedEventArgs e)\r\n at System.Windows.Freezable.OnPropertyChanged(DependencyPropertyChangedEventArgs e)\r\n at System.Windows.DependencyObject.NotifyPropertyChange(DependencyPropertyChangedEventArgs args)\r\n at System.Windows.DependencyObject.UpdateEffectiveValue(EntryIndex entryIndex, DependencyProperty dp, PropertyMetadata metadata, EffectiveValueEntry oldEntry, EffectiveValueEntry& newEntry, Boolean coerceWithDeferredReference, Boolean coerceWithCurrentValue, OperationType operationType)\r\n at System.Windows.DependencyObject.InvalidateProperty(DependencyProperty dp)\r\n at System.Windows.Data.BindingExpression.TransferValue(Object newValue, Boolean isASubPropertyChange)\r\n at MS.Internal.Data.PropertyPathWorker.UpdateSourceValueState(Int32 k, ICollectionView collectionView, Object newValue, Boolean isASubPropertyChange)\r\n at MS.Internal.Data.PropertyPathWorker.Upd

ateSourceValueState(Int32 k, ICollectionView collectionView)\r\n at MS.Internal.Data.ClrBindingWorker.OnSourcePropertyChanged(Object o, String propName)\r\n at MS.Internal.Data.PropertyPathWorker.System.Windows.IWeakEventListener.ReceiveWeakEvent(Type managerType, Object sender, EventArgs e)\r\n at System.Windows.WeakEventManager.DeliverEventToList(Object sender, EventArgs args, ListenerList list)\r\n at System.ComponentModel.PropertyChangedEventManager.OnPropertyChanged(Object sender, PropertyChangedEventArgs args)\r\n at GenesysShell.DataPointSetViewModel.RaisePropertyChanged(String  propertyName) in C:\\Data\\tfs\\...\\MainView.xaml.cs:line 50\r\n at ....DataPointSetViewModel.set_Load(DataView value) in C:\\Data\\tfs\\...\\Views\\MainView.xaml.cs:line 69\r\n at ....MainView.cmdProcess_Click(Object sender, RoutedEventArgs e) in C:\\Data\\tfs\\...\\Views\\MainView.xaml.cs:line 268"

TargetSite: {System.Reflection.MethodInfo FindMethod(System.Type, System.String, System.Type[], System.Linq.Expressions.Expression[], System.Reflection.BindingFlags)}

This thread:
http://www.telerik.com/community/forums/wpf/chart/error-in-aplying-aggregate-function-when-binding-from-datatable.aspx
talks about setting the "FieldType" to double for correcting a similar error, like so:

But I'm using wpf design-time binding, not c#--how would this be done in xaml (as I get an error):

<charting:ItemMapping FieldName="Value" DataPointMember="YValue" FieldType="double">
</charting:ItemMapping>
?

My XAML looks like this:

<UserControl ...

<telerik:RadChart x:Name="chartSegTrak" Margin="0,45,0,10" UseDefaultLayout="False">

    <charting:ChartArea x:Name="segTrakChartArea" EnableAnimations="False">
    </charting:ChartArea>
                   
    <telerik:RadChart.SeriesMappings>
        <charting:SeriesMapping ChartAreaName="ChartArea" ItemsSource="{Binding Load}">

            <charting:SeriesMapping.SeriesDefinition>
                <charting:LineSeriesDefinition>
                </charting:LineSeriesDefinition>
            </charting:SeriesMapping.SeriesDefinition>

            <charting:ItemMapping FieldName="Value" DataPointMember="YValue">
            </charting:ItemMapping>

        </charting:SeriesMapping>

    </telerik:RadChart.SeriesMappings>

</telerik:RadChart>
...

The code-behind looks like this:

    //
    // ViewModel code...
    //
    public class DataPointSetViewModel : INotifyPropertyChanged
    {
        private string _name;

        public DataPointSetViewModel(){}

        public event PropertyChangedEventHandler PropertyChanged;

        protected void RaisePropertyChanged(String propertyName)
        {
            PropertyChangedEventHandler handler = this.PropertyChanged;

            if (handler != null)
                handler(this, new PropertyChangedEventArgs(propertyName));
        }

        public DataView Load
        {
            set
            {
                _load = value;
                RaisePropertyChanged("Load");               
            }
            get
            {
                return _load;
            }
        }
        ...
    }

 //
 // Window/UserControl code...
 //
 public partial class MainView : UserControl
 {
        DataPointSetViewModel _vm;

        public MainView()
        {
            _vm = new DataPointSetViewModel();
            this.DataContext = _vm; 
            InitializeComponent();
        }
...
        private void cmdProcess_Click(object sender, RoutedEventArgs e)
        {
            ...

            try
            {
...
                DataView dvLoad = new DataView(<someclass>.DataSet.GenesysDataPoint);
                dvLoad.RowFilter = "StudyId=5 AND GlobalResourceId=2";
                dvLoad.Sort = "Year, Month, Day, Hour";
                _vm.Load = dvLoad;
            }
            catch (Exception ex)
            {
                Cursor = System.Windows.Input.Cursors.Arrow;
                MessageBox.Show("Error: " + ex.ToString());
            }
        }

The UserControl's DataContext is set and I can two-way bind simple properties with success.  It's just the DataView two-way binding that's not working correctly.  Thanks!