Fading Thumbnail

I have this thing I want to do. I have a black square with a black border. I made a the square a movie clip and then made a new symbol. I then placed the border and the square movie clip in the new symbol. Then on the square, which was a movie clip, I put this:

on(rollOver) {
if(this._alpha > 0) {
this._alpha -=5;
}
}
on(rollOut) {
if(this._alpha < 40) {
this._alpha +=5;
}
}

But it didn’t seem to work :h: It kinda just faded out a little bit. So basically what I want to do is have ti so that there is a picture with a border and a little bit of a black tint to it. Then when you mouse over it, I want the tint to fade.