Movie Storyboard doesn't work

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XAML

WPF

Hi
I want to play a movie on the start of my program then show a white rectangle quickly after the movie is finished then fade out the movie an rectangle with wpf animations.

What I did was I used the MediaEnded event of the media element to start the animation of the white rectangle fade out. But when i run the program it doesn't animate the opacity of the rectangle. it just waits for 1 second (the animation duration) and it disappears!

I have tried to use the XAML for creating the storyboard and playing it with triggers in Expression Blend but that didn't work either.
here is my code:

//'movie' is the MediaElement and 'rect' is the white Rectangle that appears after the movie is finished and fades out

private void movie_MediaEnded(object sender, RoutedEventArgs e)
        {
            movie.Opacity = 0.0;
            rect.Opacity = 1.0;
            Storyboard fadeOut = new Storyboard();
            fadeOut.Completed += new EventHandler(fadeOut_Completed);
            DoubleAnimation fadeOutAnimation = new DoubleAnimation { Duration = TimeSpan.FromSeconds(1), To = 0.0 };
            Storyboard.SetTargetProperty(fadeOutAnimation, new PropertyPath("Opacity"));
            fadeOut.Children.Add(fadeOutAnimation);
            fadeOut.Begin(rect);
        }

        void fadeOut_Completed(object sender, EventArgs e)
        {
            rect.Visibility = Visibility.Collapsed;
            movie.Visibility = Visibility.Collapsed;
        }

sorry for the long question!
thanks!