Problem with transition effect

after performing a transition effect on a movie clip (as3), the mouseDown listener stops working until click somewhere else on the stage or click a couple of times on the movie clip.

//example code
MovieClip.addEventListener(MouseEvent.MOUSE_DOWN, myfunc);

//transition effect example
TransitionManager.start(MovieClip1, {type:Squeeze, direction:Transition.IN, duration:2, easing:Elastic.easeOut, dimension:1});

anyone can help ??