when set radtreeviewitem.IsEditable=true Error:Value does not fall within the expected range

[John]

when i set radtreeviewitem.IsEditable=true  then throw  Error:Value does not fall within the expected range

code is :
    <Grid>
 <Grid.Resources>
  <DataTemplate x:Key="EDITTeam">
         <StackPanel Orientation="Horizontal">
             <TextBox Text="" Width="100"/>
             <TextBlock Text=" | Count#"/>
             <TextBlock Text="  "/>
    <app:ButtonEx Content="取消编辑" Action="CancelEdit" ActionParam=""/>
         </StackPanel>
     </DataTemplate>
 </Grid.Resources>
 <telerik:RadTreeView x:Name="radTreeView"
 IsDragDropEnabled="True" IsEditable="True"
 ItemEditTemplate="{StaticResource EDITTeam}">
<telerik:RadTreeViewItem>
   <telerik:RadTreeViewItem.Header>
   <StackPanel Orientation="Horizontal">
    <TextBlock Text="test" Margin="0,3,0,0"/>
    <TextBlock Text="    "/>
    <!--<app:ButtonEx Content="AddChildItem" Action="ADD" />-->
   </StackPanel>
   </telerik:RadTreeViewItem.Header>
</telerik:RadTreeViewItem>
</telerik:RadTreeView>

Python:
treemain.SelectedItem.IsEditable=True

[Hristo]

Hello,

I've tried to simulate the issue but with no avail. Could you please modify the attached project in order to simulate the issue so we can investigate in detail.

Looking for your answer.

Regards,
Hristo
the Telerik team