There is an issue that When I do according to the Demo you offer I can't finish correctly that the positive value display with red and the negative value display with blue.In other words one of SeriesMapping of Chart displays with bicolour with positive value and negative value.
As the example have errors.
xmlns:example="clr-namespace:Telerik.Windows.Examples.Chart.MVVM">
<UserControl.DataContext>
<example:ExampleViewModel />
</UserControl.DataContext>
The program can't use ExampleViewModel.