I am trying to create the simplest Silverlight templated control, and I can't seem to get TemplateBinding to work on the Angle property of a RotateTransform.

Here's the ControlTemplate from generic.xaml:

<ControlTemplate TargetType="local:CtlKnob">
  <Grid x:Name="grid" RenderTransformOrigin="0.5,0.5">
    <Grid.RenderTransform>
      <TransformGroup>
         <RotateTransform Angle="{TemplateBinding Angle}"/> <!-- This does not work -->
         <!-- <RotateTransform Angle="70"/> -->             <!-- This works -->
      </TransformGroup>
    </Grid.RenderTransform>
    <Ellipse Stroke="#FFB70404" StrokeThickness="19"/>
    <Ellipse Stroke="White" StrokeThickness="2" Height="16" VerticalAlignment="Top"
       HorizontalAlignment="Center" Width="16" Margin="0,2,0,0"/>
  </Grid>
</ControlTemplate>

Here's the C#:

using System.Windows;
using System.Windows.Controls;

namespace CtlKnob
{
  public class CtlKnob : Control
  {
    public CtlKnob()
    {
      this.DefaultStyleKey = typeof(CtlKnob);
    }

    public static readonly DependencyProperty AngleProperty = 
        DependencyProperty.Register("Angle", typeof(double), typeof(CtlKnob), null);

    public double Angle
    {
      get { return (double)GetValue(AngleProperty); }
      set { SetValue(AngleProperty,value); }
    }
  }   
}