Tween Alpha MovieClips

MovieClip.prototype.incAlpha = function(time){
	var myClip = this;
	var myTween:Tween = new Tween(myClip, "_alpha", mx.transitions.easing.Regular.easeOut, 0, 100, time, false);
	myTween.onMotionFinished = function(){myClip._visible=true;}
};
 
MovieClip.prototype.decAlpha = function(time){
	var myClip2 = this;
	var myTween:Tween = new Tween(myClip2, "_alpha", mx.transitions.easing.Regular.easeOut, 100, 0, time, false);
	myTween.onMotionFinished = function(){myClip2._visible=false;}
};