CategoricalSeriesDescriptor.TypePath is not currently bindable. This means this has to point to a property on your DataSource that returns Telerik series types. This breaks the MVVM design model, as the DataSource points to the ViewModel, that should not contain any View specific types. Please provide a bindable alternative, such that a Converter can be applied to supply the View specific types.

Will be available in Q1 2016 Release.