Beginner needing a bit of help

I have two frames so far in my movie. The first is the background and the second is the background (very transparent) with a new image highlighted on top. I want the viewer to be able to rollover a section in the background with the mouse (dance_mc) and view the second frame, then roll back out and be back on the background. I am going to do this with a few places once I get it working. Below is my code. I know most of it is working because when I test it with the alpha it works. But the gotoAndPlay does not work. I have the stop(); because without it the movie just plays continuously. What am I doing wrong?

stop();

dance_mc.addEventListener(MouseEvent.ROLL_OVER, mouseOverHandler);
dance_mc.addEventListener(MouseEvent.ROLL_OUT, mouseOutHandler);

function mouseOverHandler(event:MouseEvent):void
{
dance_mc.alpha = .5;
dance_mc.gotoAndPlay(2);
}

function mouseOutHandler(event:MouseEvent):void
{
dance_mc.alpha = 1;
dance_mc.gotoAndPlay(1);

}

dance_mc.buttonMode = true; // enables use of hand cursor