Gallery question, thumbnails not disappearing

So, I succesfully built a gallery. However, the thumbnails dont go away, they just get put up on top of each other and i dont want this to happen, just want them to go away when i switch galleries. I use the same method for getting rid of the clicked pick, and it goes away.

can anyone help me out…

stop();

import com.greensock.*;
import com.greensock.easing.*;

var picLoc:String;
var galNum:Number = 0;
var thumbContent:Loader = new Loader;
var thumbHolder:MovieClip = new MovieClip();
var imageHolder:MovieClip = new MovieClip();
var picLoad:Loader = new Loader();
var myXML:XML;
var myloader:URLLoader = new URLLoader();
var picLoader:Loader;
var total:Number = 0;
var gallery:Sprite = new Sprite();
var galleryPic:Sprite = new Sprite();

bkg.alpha = .3;

//gallery buttons
gal0.addEventListener(MouseEvent.MOUSE_DOWN, bw);
gal1.addEventListener(MouseEvent.MOUSE_DOWN, cp);
gal2.addEventListener(MouseEvent.MOUSE_DOWN, ls);
gal3.addEventListener(MouseEvent.MOUSE_DOWN, pl);
stage.addEventListener(Event.ENTER_FRAME, stageStop);
stage.addEventListener(MouseEvent.MOUSE_MOVE, stageMove);


function stageMove(event:MouseEvent):void {


	if (bkg.alpha < 1) {
		bkg.alpha += .05;



	} else if (bkg.alpha > 1) {

		bkg.alpha = 1;

	} else if (bkg.alpha < .3) {
		bkg.alpha = .3;
	}
	/*if (thumbHolder.alpha < 1) {
	thumbHolder.alpha += .05;
	
	
	
	} else if (thumbHolder.alpha > 1) {
	
	thumbHolder.alpha = 1;
	
	} else if (thumbHolder.alpha < .3) {
	thumbHolder.alpha = .3;
	}*/
}




function stageStop(event:Event):void {

	TweenLite.to(bkg, .5, {alpha: .3});

}



function bw(event:MouseEvent):void {


	removeThumbs();
	galNum = 0;




}

function cp(event:MouseEvent):void {

	removeThumbs();

	galNum = 1;



}

function ls(event:MouseEvent):void {

	removeThumbs();


	galNum = 2;

}

function pl(event:MouseEvent):void {

	removeThumbs();
	galNum = 3;

}

function callPics():void {


	myloader.load(new URLRequest("gallery.xml"));
	myloader.addEventListener(Event.COMPLETE, process);

}

function process(e:Event):void {


	myXML = new XML(e.target.data);
	addChild(thumbHolder);
	total = myXML.Gallery[galNum].Image.length();
	for (var i:int = 0; i < total; i++) {

		picLoc = myXML.Gallery[galNum].Image*.@picURL;
		var thumbLoc:String = myXML.Gallery[galNum].Image*.@thumb;


		var picLoader = new Loader();
		var thumbLoader = new Loader();
		thumbLoader.name = i;
		thumbLoader.x =(thumbLoader.width + 55) * i;
		thumbLoader.y = 480;
		thumbLoader.name = i;

		thumbLoader.load(new URLRequest(thumbLoc));
		picLoader.load(new URLRequest(picLoc));

		thumbLoader.contentLoaderInfo.addEventListener(Event.COMPLETE, thumbLoaded);

	}

}

function thumbLoaded(event:Event):void {


	thumbContent = Loader(event.target.loader);
	thumbHolder.addChild(thumbContent);
	thumbContent.alpha = 0;



	TweenLite.to(thumbContent, 2, {alpha: 1});


	thumbHolder.x = (stage.width - (thumbHolder.width)) / 2;

	thumbHolder.addEventListener(MouseEvent.CLICK, gallerySet);

}


function removeThumbs():void {

	thumbContent.unload();
	callPics();

}


function removeFull():void {

	//picLoad.unload();

}

function gallerySet(event:MouseEvent):void {


thumbContent.unload();

	picLoad.load(new URLRequest(myXML.Gallery[galNum].Image[event.target.name].@picURL));
	addChild(imageHolder);
	imageHolder.x = 250;
	imageHolder.y = 50;
	imageHolder.addChild(picLoad);

	picLoad.alpha = 0;

	TweenLite.to(picLoad, 2, {alpha: 1});

}