NullReferenceException in GridViewRow.OnIsExpandedChanged

[Alex]

Hello!
Found one problem with radgridviev, which I dont know how to fix.

My scenario:

WPF app for .NET Framework 4
Windows 7 (x64) Ultimate
Version of Telerik dll's: 2011.1.419.40

Here's a structure of document that i'm querying from data source:
Client 
-- Animals
----- Receptions 
(there's other relations like Client - Contacts and so on...)

I show the data to user using the following hierarchy:

RadGridView (showing clients)
-- TabControl
----- RadGridView (showing animals)
---------- TabControl
--------------- RadGridView (showing receptions)


Now, for the problem:

Every RadGridView in hierarchy has handlers for: SelectionChanged, Deleted, RowEditEnded. 
When i add any of SelectionChanged, Deleted, RowEditEnded handler to receptions RadGridView my app shows only the clients grid (the topmost one) with "+" that's not expandable.
Without handlers everything (in leaf RadGridView) works as expected.
If i use a debugger it shows that i have exception: NullReferenceException that's throwed from GridViewRow.OnIsExpandedChanged.

Here's a part of xaml i use :
http://pastebin.com/84hQ9rAP

Any suggestions about what am i doing wrong?

EDIT: 

if i delete "RowStyleSelector="{StaticResource ReceptionRowStyleSelector}" and add handlers to my nested grid - then all seems to work again an there's no exception. But i have no row styling for grid.

That's my ReceptionRowStyleSelector code:

public class ReceptionRowStyleSelector : StyleSelector<br>  
{
  public override Style SelectStyle(object item, DependencyObject container)
  {            
if (item is Reception)   
{  
            var reception = (Reception)item;
            if (reception.IsCompleted) return CompletedReception;
            if (reception.IsCanceledByClient) return CanceledReception;
    if (reception.IsClientNotified) return NotifiedReception;
 }
return DefaultStyle;
 }

...

Styles i use a very simple:

<local:ReceptionRowStyleSelector x:Key="ReceptionRowStyleSelector">
            <local:ReceptionRowStyleSelector.DefaultStyle>
                <Style TargetType="telerik:GridViewRow"></Style>
            </local:ReceptionRowStyleSelector.DefaultStyle>
            <local:ReceptionRowStyleSelector.CompletedReception>
                <Style TargetType="telerik:GridViewRow">
                    <Setter Property="Background" Value="#4502FF49"/>
                </Style>
            </local:ReceptionRowStyleSelector.CompletedReception>
            <local:ReceptionRowStyleSelector.CanceledReception>
                <Style TargetType="telerik:GridViewRow">
                    <Setter Property="Background" Value="#40000000"/>                
                </Style>
            </local:ReceptionRowStyleSelector.CanceledReception>
            <local:ReceptionRowStyleSelector.NotifiedReception>
                <Style TargetType="telerik:GridViewRow">
                    <Setter Property="Background" Value="#4FA4B700"/>
                </Style>
            </local:ReceptionRowStyleSelector.NotifiedReception>
        </local:ReceptionRowStyleSelector>

Thanks, Alex Yakimaskiy

[Vlad]

Hello Alex,

 Please get our latest internal build. We believe that we've already fixed this. 

All the best,
Vlad
the Telerik team