Stuck trying to animate mc's - see code

[Leftyplayer]

Here's the full code, basically there are four shapes in the library. Something's not working in my loop and/or my animateShapes function. The goal is to have the shapes in the loop placed on stage in random colors/transparencies and move around randomly on the stage (varying velocity) while staying within the stage boundaries. Right now, I have one little shape (the first one in the loop, I think) making an anemic motion and the rest don't move at all.

import flash.display.MovieClip;
import flash.events.KeyboardEvent;
import flash.events.Event;
import flash.text.*;

var tl:MovieClip = new Topleft();
var tr:MovieClip = new Topright();
var bl:MovieClip = new Bottomleft();
var br:MovieClip = new Bottomright();

var myShapes:Array = [tl, tr, bl, br];
//trace(myShapes);

var xVelocity: Number = 0;
var yVelocity:Number = 0;


var long:uint = myShapes.length;
for (var i:uint = 0; i < long; i++){
var shape:MovieClip = myShapes[i];
shape.alpha = 0.3 + Math.random() * 0.9;

var colorInfo:ColorTransform = shape.transform.colorTransform;
colorInfo.color = 0xffffff * Math.random();
shape.transform.colorTransform = colorInfo;

shape.velX = Math.random()*10-5
shape.velY = Math.random()*10-5

shape.posX = shape.x = Math.random() * stage.stageWidth;
shape.posY = shape.y = Math.random() * stage.stageHeight;
addChild(shape);

shape.addEventListener(Event.ENTER_FRAME, animateShapes);
}

function animateShapes(evt:Event):void
{
var s:MovieClip = MovieClip(evt.currentTarget);
shape.posX += shape.velX;
shape.posY += shape.velY;

if(shape.y <= stage.stageHeight-shape.length/2){
shape.posY -= shape.velY;}
if(shape.x <= stage.stageWidth-shape.width/2){
shape.posX -= shape.velX;}
shape.x = shape.posX;
shape.y = shape.posY;
}