Remove child problem

programming flash
1

I have this code, and in the end, where I am trying to removeChild(ball) I get an error:

1118: Implicit coercion of a value with static type Object to a possibly unrelated type flash.display:DisplayObject.



for (var i:uint = 0; i < 50; i++) {
    var ball:Ball = new Ball();
    ball.x = Math.random() *reference_mc.width + reference_mc.x;
    ball.y = Math.random() *reference_mc.height + reference_mc.y;
    addChild(ball);
    ball.addEventListener(Event.ENTER_FRAME, everyFrame);
}

function everyFrame(e:Event):void {

  **  var ball:Object = e.target;**

    var dx:Number = ball.x - parent.mouseX;
    var dy:Number = ball.y - parent.mouseY;
    var angle = Math.atan2(dy, dx);
    var dist:Number = Math.sqrt(dx*dx + dy*dy);
    var accel:Number = (range - dist) * accelFactor;
    if (accel > 0) {
        speed += accel;
    }
    speed *= decelFactor;
    ball.x += speed * Math.cos(angle);
    ball.y += speed * Math.sin(angle);

    //remove them if they exit screen
    if (ball.x - ball.width/2 > stage.stageWidth || ball.x + ball.width/2 < 0 || ball.y - ball.width/2 > stage.stageHeight || ball.y + ball.width/2 < 0) {
        **removeChild(ball);**
    }
}