Can't seems to completely removeChild

programming flash
1

I have this gradient backgroun where it goes from 0-100-0 of alpha.
When I rollover a button, I add in the bg, and when i rollout of the bg, i remove it.
The problem now is when I rollover the button the 2nd time,
it seems like the bg added already have a previous added gradient bg, and it added a new 1 on top.
so each time I rollover the button the alpha of the gradient will go higher

exp:
1st time rollover:0-100-0
2nd time rollover:10-100-10
3rd time rollover:20-100-20
etc.

what could be the problem here?

private function bgGlow(event:Object):void {
            square.visible=true;
            //Disable menu below
            event.parent.button.visible=false;

            // Glowing Background
            var type:String=GradientType.LINEAR;
            var colors:Array=[0xFFFFFF,0xFFFFFF,0xFFFFFF,0xFFFFFF,0xFFFFFF];
            var alphas:Array=[0,1,1,1,0];
            var ratios:Array=[0,50,155,180,255];
            var spreadMethod:String=SpreadMethod.PAD;
            var interp:String=InterpolationMethod.LINEAR_RGB;
            var focalPtRatio:Number=0;

            var matrix:Matrix = new Matrix();
            var boxWidth:Number=145;
            var boxHeight:Number=500;
            var boxRotation:Number=Math.PI/2;// 90¡ã 
            var tx:Number=0;
            var ty:Number=0;
            matrix.createGradientBox(boxWidth, boxHeight, boxRotation, tx, ty);

            square.graphics.beginGradientFill(type,  
                                        colors, 
                                        alphas, 
                                        ratios,  
                                        matrix,  
                                        spreadMethod,  
                                        interp,  
                                        focalPtRatio);
            square.graphics.drawRect(0, 0, 145, 600);

            square.x=event.parent.x;
            square.y=-320;

             addChild(square);

            this.buttonMode=true;
            this.addEventListener(MouseEvent.ROLL_OUT,btnOut);
        }

private function btnOut(event:MouseEvent):void {
            //Enable menu button
            event.target.menuArray[0].button.visible=true;
            event.target.menuArray[1].button.visible=true;
            event.target.menuArray[2].button.visible=true;
            event.target.menuArray[3].button.visible=true;
            event.target.menuArray[4].button.visible=true;

            removeChild(square);
            removeEventListener(Event.ENTER_FRAME,bgGlow);
        }

I also tried remove the whole function but it doesnt seems to work too.

And how do I combine the array functions?