Prototype fade in

Hi guys
i’m trying to play prototype.
Came up with this idea case for now

//function fade in
MovieClip.prototype.fadein = function (){
this._alpha=0
this._alpha +=1
this.onEnterFrame = function (){
if (this._alpha>99){
this._alpha = 100
delete this.onEnterFrame
}
}
}
mc_container.onEnterFrame = function(){
this.fadein();
mc_container.loadMovie(“test.swf”)
};

It doesn’t seem to work : S: S what i do wrong??