New Post: Dropdown button and propertygrid

Hello

I am trying to add a drop down button with a tree view to your property grid.

The drop down button appears but when I select it, I get no drop down at all (I get a tiny black square). Any ideas what I am doing wrong?

<xctk:DropDownButton x:Class="Xceed.Wpf.Toolkit.PropertyGrid.Implementation.Editors.DataSourceEditor"
      xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
      xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
      xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" 
      xmlns:d="http://schemas.microsoft.com/expression/blend/2008" 
      xmlns:xctk="clr-namespace:Xceed.Wpf.Toolkit"
      mc:Ignorable="d" HorizontalAlignment="Right" IsOpen="True" Content="Blah">
     
     <xctk:DropDownButton.DropDownContent>
        <TreeView>
        <TreeViewItem Header="Well">
                <TreeViewItem Header="sample1"/>
                <TreeViewItem Header="sample2"/>
                <TreeViewItem Header="sample3"/>
            </TreeViewItem>
        </TreeView>
    </xctk:DropDownButton.DropDownContent>
</xctk:DropDownButton>

The drop down appears fine in my XAML design viewer. I am using VS2010.

Thanks