Value does not fall within the expected range in DataGridDragDropTarget

Question

I am using silverlight 5 and getting an error in designer saying Value does not fall within the expected range when I put a user control inside the DataGridDragDropTarget. And my user control is basicall a datagrid. Below is the code:

  <StackPanel Orientation="Horizontal">
        <toolkit:DataGridDragDropTarget AllowedSourceEffects="Copy"
                                        VerticalAlignment="Top">
              <views:CustomerGrid x:Name="customerGrid" d:LayoutOverrides="Width, Height" />
        </toolkit:DataGridDragDropTarget>
    </StackPanel>

Answer 1

Are you sure you don't have any other controls named "customerGrid" on your page?

Answer 2

Try deleting bin Debug\release folders, putting x:name to panel, or, as ghost_mv says, check that there is'nt other control with the same name.