Vista - Runtime crash while data binding

I am trying to bind an element's value to a public property of one of my
objects. The property, named "Text", is of type string. The control is
working fine ( until I try and do this binding ). Here's the databinding
string:

<t:MyControl Grid.Row="1" Text="{Binding ElementName=mProjectTree,
Path=SelectedValue.Name}" />

I'm getting this error:

"Error at element 'RuntimePropertyInfo' in markup file 'MainWindow.xaml' :
Object of type 'System.Windows.Data.Binding' cannot be converted to type
'System.String'.."

Now when I use that exact same binding expression on a TextBox, like so:


<TextBox BorderThickness="0" Text="{Binding ElementName=mProjectTree,
Path=SelectedValue.Name}">

</TextBox>


I don't have any problems. What am I doing wrong?

Thanks,

CS