Fade a mc on click of another button

1

I’m trying to fade a movieclip by clicking on a button. On the main timeline I have just a circle graphic movieclip with instance name ball, then I also have two buttons on the main timeline with the following as:


on (release) {
if (_root.ball._alpha <=0) {
_root.ball._alpha +10;
}
}

That’s on the button to increase the opacity
Then on the button to decrease opacity I have:


on (release) {
if (_root.ball._alpha >=100) {
_root.ball._alpha -10;
}
}

No luck.Also would it be possible to make a slider bar to adjust the opacity of the ball mc?

Thanks