On(release) making an images alpha to drop by 10s?

ok, I have this bg photo and I need it to fade out completely and load another one in its place, and I want to do this with only actionscript… right now when you click the button to make the image fade out it only fades the alpha 10 lower… heres my code so far…\

on(release) {
    _level2._alpha -= 10;
    if(_level2._alpha <= 1){
        loadMovieNum("aboutPageMain.swf","2");
        }
}

is there something I can do in the code to make the alpha continue to drop until it hits 0? thanks in advance if its possible.