Stop a StoryBoard

Hi,

I have a story boards with some animations and a repeat behaviour which is set to forever.

I want to stop my storyboard at a point in my programm,but it doesn't work.

I created a function/object  and I call it whenever I need.

   private void StopFade()
        {
            Storyboard repeat = (Storyboard)Resources["repeat"];
            repeat.Stop(this);
        }

Issue #2 How can I make an image to transition across the screene,and I want to controll it from code behind.

Thank you!