Dynamic Movie Clip

programming flash
1

Hi,
I inrended to rewrite the code for Animating Mvie Clip.
This is my code :
[SIZE=2][FONT=courier new]package{
import flash.display.;
import flash.events.;
import flash.geom.;
import flash.text.;

public class Circles extends MovieClip{

    var rad:Number=20;
    var newCircle:MovieClip = new MovieClip();
    
    public function Circles() {

        stage.addEventListener(MouseEvent.CLICK, AddCircle);
    }

    public function AddCircle(evt:MouseEvent):void{
        
        newCircle.graphics.beginFill(0xff0000);
        newCircle.graphics.drawCircle(mouseX, mouseY, rad);
        newCircle.graphics.endFill();
        addChild(newCircle);
        newCircle.addEventListener(Event.ENTER_FRAME, zoomCircle);
    }

    function zoomCircle(evt:Event):void {
        var aCircle:MovieClip = MovieClip(evt.target);
        aCircle.scaleX += 3;
        aCircle.scaleY += 3;
    }
}

}[/FONT][/SIZE]

Now, if I commented the aCircle.scaleX and aCircle.scaleY the code draws circles but, of course, does not change their zize. If a uncommented the above lines the code draws nothing.
What is my mistake ?

Thank you.