in http://www.telerik.com/help/wpf/radchartview-populating-with-data-chartdatasource.html is this sample
MyDataSource : ChartDataSource
We used that with version 2012.3.1017.40 and it work fine for us.
Now we tried to upgrad to version 2012.3.1129.40 and is doesnt work. The property "ValueAggregateFunction" is not available