ObservableCollection DependencyProperty for new Custom FrameworkElement

Hi,

I want to create custom control which is simply occurs a grid and contains rectangle elements. I want to make databinding for the rectangle elements. Therefore I create a custom class for my grid and has a dependency property for Rectangle objects.

 public class MyGrid : Grid
 {
        public static readonly DependencyProperty TimeInformationContentProperty =
              DependencyProperty.Register("TimeInformationContent",
            typeof(ObservableCollection<Rectangle>),
            typeof(MyGrid),
            new PropertyMetadata(new ObservableCollection<Rectangle>() )
            );

        public ObservableCollection<Rectangle> TimeInformationContent
        {
            get { return (ObservableCollection<Rectangle>)GetValue(TimeInformationContentProperty); }
            set { SetValue(TimeInformationContentProperty, value); }
        }
}

Now I create a new UserControl ie. TimeControl.cs, and this control has the same DependencyProperty above. In XAML part i write:

<main:MyGrid TimeInformationContent="{Binding Path=TimeInformationContent, ElementName= Root_Part}" />

for databinding.

Then I want to use this UserContol in the MainWindow and i write this:

<Window.DataContext><main:ViewModel /></Window.DataContext><Grid><Grid.RowDefinitions><RowDefinition Height="auto" /><RowDefinition Height="*" /></Grid.RowDefinitions><main:TimeControl TimeInformationContent="{Binding RectangleContent, Mode=TwoWay}" Height="50" /></Grid>

which in ViewModel part i have an ObservableCollection for the rectangles.

Here is the questin: this code does not work.

Is there a simple mistake? or the concept for this scenario is totaly wrong?

King Regards