Silverlight DatePicker in DataGrid: Enter does not submit

Question

I have DataGrid with DataGridTemplateColumn which has DatePicker as editing element:

    <data:DataGridTemplateColumn Header="Due date" CanUserSort="False" >
         <data:DataGridTemplateColumn.CellTemplate>
             <DataTemplate>
                <TextBlock Text="{Binding EndDateFormatted}" />
             </DataTemplate>
         </data:DataGridTemplateColumn.CellTemplate>
         <data:DataGridTemplateColumn.CellEditingTemplate>
             <DataTemplate>
                 <controls:DatePicker SelectedDate="{Binding EndDate, Mode=TwoWay}" />
             </DataTemplate>
         </data:DataGridTemplateColumn.CellEditingTemplate>
    </data:DataGridTemplateColumn>

The problem is that Enter key does not work at all when in textbox editing mode - just does nothing. Selecting date from dropdown panel works. Also, Tab does not keep value (reset to previous one), but with help of this I can fix it. But I don't know how to make Enter to accept value and preferably move to next cell.

I also tried third-party date picker, no changes - same issues with Tab and Enter. Seems like a DataGrid issue.

I use Silverlight 3.