Problem Removing Children

Question

I'm having trouble removing some preloader movieclips I have inserted via AS3. The message I get is:
ArgumentError: Error #2025: The supplied DisplayObject must be a child of the caller.
at flash.display::DisplayObjectContainer/removeChild()
at btn5_fla::MainTimeline/thumbLoaded()
for every preloader a loaded, except the last one.
My code is:
import caurina.transitions.*;
var indexXML:XML;
var columns:Number;
var thumbWidth:Number;
var thumbHeight:Number;
var myThumbs:XMLList;
var totalThumbs:Number;
var preloader:LoaderAnim;
var container:MovieClip;
var xCounter:Number = 0;
var yCounter:Number = 0;
var xmlReq:URLRequest = new URLRequest("clientes.xml");
var xmlLoader:URLLoader = new URLLoader();
scrollbox.ch.client_info.autoSize = TextFieldAutoSize.LEFT;
scrollbox.ch.client_info.htmlText = "";
scrollbox.sb.visible = false;
scrollbox.sb.alpha = 0;
function urlLoaded(e:Event):void{
indexXML = new XML(e.target.data);
columns = indexXML.logos.@columns;
thumbWidth = indexXML.logos.@width;
thumbHeight = indexXML.logos.@height;
myThumbs = indexXML.logos.*;
totalThumbs = myThumbs.length();
scrollbox.ch.client_info.htmlText += indexXML.intro;
createContainer();
callThumbs();
function createContainer():void{
container = new MovieClip();
scrollbox.ch.addChild(container);
container.y = scrollbox.ch.client_info.height + scrollbox.ch.client_info.y + 20;
function callThumbs():void{
for(var i:Number = 0; i<totalThumbs; i++){
var thumbURL = myThumbs[i].@thumb;
trace("Loading "+thumbURL);
var thumbLoader = new Loader();
thumbLoader.load(new URLRequest(thumbURL));
thumbLoader.contentLoaderInfo.addEventListener(Event.COMPLETE, thumbLoaded);
thumbLoader.x = (thumbWidth+40)*xCounter;
thumbLoader.y = (thumbHeight+40)*yCounter;
if (xCounter+1 < columns){
xCounter++;
}else {
xCounter=0;
yCounter++;
preloader = new LoaderAnim();
preloader.name = "preloader"+i;
trace(preloader.name);
preloader.x = thumbLoader.x+30;
preloader.y = thumbLoader.y+30;
container.addChild(preloader);
function thumbLoaded(e:Event):void{
var thb:Loader = Loader(e.target.loader);
container.addChild(thb);
if(scrollbox.ch.height<scrollbox.masker.height){
scrollbox.sb.visible = false;
}else{
scrollbox.sb.visible = true;
Tweener.addTween(scrollbox.sb, {alpha:1, time:1});
container.removeChild(preloader);
xmlLoader.addEventListener(Event.COMPLETE, urlLoaded);
xmlLoader.load(xmlReq);

Answer 1

import caurina.transitions.*; 
var indexXML:XML;
var columns:Number;
var thumbWidth:Number;
var thumbHeight:Number;
var myThumbs:XMLList;
var totalThumbs:Number;
var i:uint=0;
var preloader:LoaderAnim;
var container:MovieClip;
var xCounter:Number = 0;
var yCounter:Number = 0;
var xmlReq:URLRequest = new URLRequest("clientes.xml");
var xmlLoader:URLLoader = new URLLoader();
scrollbox.ch.client_info.autoSize = TextFieldAutoSize.LEFT;
scrollbox.ch.client_info.htmlText = "";
scrollbox.sb.visible = false;
scrollbox.sb.alpha = 0;
function urlLoaded(e:Event):void{
indexXML = new XML(e.target.data);
columns = indexXML.logos.@columns;
thumbWidth = indexXML.logos.@width;
thumbHeight = indexXML.logos.@height;
myThumbs = indexXML.logos.*;
totalThumbs = myThumbs.length();
scrollbox.ch.client_info.htmlText += indexXML.intro;
createContainer();
callThumbs();
function createContainer():void{
container = new MovieClip();
scrollbox.ch.addChild(container);
container.y = scrollbox.ch.client_info.height + scrollbox.ch.client_info.y + 20;
function callThumbs():void{
//for(var i:Number = 0; i<totalThumbs; i++){
var thumbURL = myThumbs[i].@thumb;
trace("Loading "+thumbURL);
var thumbLoader = new Loader();
thumbLoader.load(new URLRequest(thumbURL));
thumbLoader.contentLoaderInfo.addEventListener(Event.COMPLETE, thumbLoaded);
thumbLoader.x = (thumbWidth+40)*xCounter;
thumbLoader.y = (thumbHeight+40)*yCounter;
if (xCounter+1 < columns){
xCounter++;
}else {
xCounter=0;
yCounter++;
preloader = new LoaderAnim();
preloader.name = "preloader"+i;
trace(preloader.name);
preloader.x = thumbLoader.x+30;
preloader.y = thumbLoader.y+30;
container.addChild(preloader);
function thumbLoaded(e:Event):void{
var thb:Loader = Loader(e.target.loader);
container.addChild(thb);
if(scrollbox.ch.height<scrollbox.masker.height){
scrollbox.sb.visible = false;
}else{
scrollbox.sb.visible = true;
Tweener.addTween(scrollbox.sb, {alpha:1, time:1});
container.removeChild(preloader);
i++;
if(i<totalThumbs){
callThumbs();
xmlLoader.addEventListener(Event.COMPLETE, urlLoaded);
xmlLoader.load(xmlReq);