IndexOutOfRangeException when sorting

[Mattias]

Is this not possible to achieve?

<telerik:GridBoundColumn SortExpression="Registrations.RegisteredOrganisationName" UniqueName="RegisteredOrganisationName" HeaderText="Organisation name" DataField="RegisteredOrganisationName" HtmlEncode="true" />

Here is the error message i receive (translated from swedish):

[IndexOutOfRangeException: Cant find the column Registrations.RegisteredFirstName.]
   System.Data.DataTable.ParseSortString(String sortString) +6235165
   System.Data.DataView.CheckSort(String sort) +35
   System.Data.DataView.set_Sort(String value) +155
   Telerik.Web.UI.GridEnumerableFromDataView.PerformTransformation() +3177
   Telerik.Web.UI.GridEnumerableFromDataView.TransformEnumerable() +24
   Telerik.Web.UI.GridTableView.GetEnumerator(Boolean useDataSource, GridEnumerableBase resolvedDataSource, ArrayList dataKeysArray) +164
   Telerik.Web.UI.GridTableView.CreateControlHierarchy(Boolean useDataSource) +514
   Telerik.Web.UI.GridTableView.CreateChildControls(IEnumerable dataSource, Boolean useDataSource) +608
   System.Web.UI.WebControls.CompositeDataBoundControl.PerformDataBinding(IEnumerable data) +72
   System.Web.UI.WebControls.DataBoundControl.OnDataSourceViewSelectCallback(IEnumerable data) +147
   System.Web.UI.WebControls.DataBoundControl.PerformSelect() +261
   Telerik.Web.UI.GridTableView.PerformSelect() +23
   Telerik.Web.UI.GridTableView.DataBind() +363
   Telerik.Web.UI.GridSortCommandEventArgs.ExecuteCommand(Object source) +243
   Telerik.Web.UI.RadGrid.OnBubbleEvent(Object source, EventArgs e) +185
   System.Web.UI.Control.RaiseBubbleEvent(Object source, EventArgs args) +70
   Telerik.Web.UI.GridItem.OnBubbleEvent(Object source, EventArgs e) +53
   System.Web.UI.Control.RaiseBubbleEvent(Object source, EventArgs args) +70
   Telerik.Web.UI.GridItem.OnBubbleEvent(Object source, EventArgs e) +115
   System.Web.UI.Control.RaiseBubbleEvent(Object source, EventArgs args) +70
   System.Web.UI.Page.RaisePostBackEvent(IPostBackEventHandler sourceControl, String eventArgument) +29
   System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) +2981
                     

[Mattias]

Nevermind. It all disappeared when i set AllowCustomSorting to true.