Quick help on custom class issue

Trying to learn how to make custom classes. Just want to have two functions from the class. One to fade a mc(circle_mc) out and another to fade it back in again. I can get the class to trace to the fla file but can’t get the movieclip to tween at all. Any help on this would be greatly appreciated.

import mx.transitions.Tween;
import mx.transitions.easing.Regular;
import mx.transitions.easing.Strong;

==================class file====================

class BallClass extends MovieClip {

private var _mcFade:MovieClip;
private var _tweener:Tween;

public function get mcFader() {
trace(“getting…”)
return _mcFade;

}

public function set mcFader(mcFade:MovieClip) {
trace(“setting…”)
_mcFade = mcFade;

}

public function fadeOut(mcFade:MovieClip) {
this._alpha = 0;
trace(“fadeout”);
}

public function fadeIn() {
this._xscale = 500;
trace(“fadein”);

}

}

==================fla file====================

var ballTest:BallClass = new BallClass();
trace(ballTest.mcFader);

ballTest.mcFader = circle_mc;
trace(ballTest.mcFader);

circle_mc.onRollOver = function () {
ballTest.fadeOut(circle_mc);
}

circle_mc.onRollOut = function () {
ballTest.fadeIn(circle_mc);
}