Roof.gotoAndPlay(2); But it stops

I’m having some trouble with playing a flash movie.

When the flash animation starts, i want to start a movie clip with instance name roof.
So i just put this in my code. : roof.gotoAndPlay(2);
Flash go’s to the secont frame, but stops there.

When i use a button to start the secont frame, it works.
So this works and plays :

stopmusic.onRelease = function(){
_root.mySound.stop();
_root.roof.gotoAndStop(1);

nextFrame();

}

What am i forgetting here?