Loading XML generated image scroller

Ok. I have abandoned that scroller for now. Its a bit above my head. Instead I have made a simple scrollpane with components in flash. I have thumbnails in a movie that is linked to the scrollpane and I have made each one a button. But I am not able to get the larger version load when I test the movie and click on one of the thumbnails. Here is the code I have put into the movie that is linked to the scrollpane:

var Xpos:Number = 275;
var Ypos:Number = 180;
var jpg:MovieClip;
var loader:Loader = new Loader();

var defaultIMAGE:URLRequest = new URLRequest("swfs/mixed_media/one.jpg");

loader.load(defaultIMAGE);
loader.x =Xpos;
loader.y =Ypos;
addChild(loader);
///////////////////////////////////////////////////////////////////

//Btns Universal function
function btnClick(event:MouseEvent):void{

removeChild(loader);
var newJPGRequest:URLRequest = new URLRequest("swfs/mixed_media/"+event.target.name+".jpg");
loader.load(newJPGRequest);
loader.x =Xpos;
loader.y =Ypos;
addChild(loader);
}
//Btn Listeners
one.addEventListener(MouseEvent.CLICK, btnClick);
two.addEventListener(MouseEvent.CLICK, btnClick);
three.addEventListener(MouseEvent.CLICK, btnClick);
four.addEventListener(MouseEvent.CLICK, btnClick);
five.addEventListener(MouseEvent.CLICK, btnClick);
six.addEventListener(MouseEvent.CLICK, btnClick);

1.  where's the background?  is that loaded into your scroller swf?

2.  you're using a mask in your scroller swf?  if yes, where's the mask and how are you assigning the mask?