XML AS3 load/unload

Question

I've got a peice of code that I use to load images for a slideshow.  Loader brings it up, adds it to the stage, tweens it in nicely. Everything works fine if the images are all the same size.  The problem is, the previous image is always there.  So if I have images of different sizes, you can still see the previous images.  How do I unload the previous image?  I can't figure out how to (unload, visible= false, alpha=0, ect) after the new image is tweened in.
This is one of those deals where I would have had it done already if I would use the timeline but if I figure out how to package it, I'll have it for next time.
Here's the code:
import fl.transitions.Tween;
import fl.transitions.easing.*;
import fl.transitions.TweenEvent;
var myTween:Tween;
var xmlRequest:URLRequest = new URLRequest("imageData.xml");
var xmlLoader:URLLoader = new URLLoader(xmlRequest);
var imgData:XML;
var imageLoader:Loader;
var rawImage:String;
var rawH:String;
var rawW:String;
var imgNum:Number = 0;
var checkSec:Timer = new Timer(100);
var delay:Timer = new Timer(3000);
var numberOfChildren:Number;
xmlLoader.addEventListener(Event.COMPLETE, xmlLoadedF);
function xmlLoadedF(event:Event):void {
    checkSec.start();
    checkSec.addEventListener(TimerEvent.TIMER, checkerF);
    imgData = new XML(event.target.data);
function packagedF():void{
    checkSec.removeEventListener(TimerEvent.TIMER, checkerF);
    rawImage = imgData.image[imgNum].imgURL;
    numberOfChildren = imgData.*.length();
    rawW = imgData.image[imgNum].imgW;
    rawH = imgData.image[imgNum].imgH;
    imageLoader = new Loader;
    imageLoader.load(new URLRequest(rawImage));
    master_mc.addChild(imageLoader);
    imageLoader.x = (master_mc.width - Number(rawW)) / 2;
    imageLoader.y = (master_mc.height - Number(rawH)) / 2;
    imageLoader.alpha = 0;
    myTween = new Tween(imageLoader,"alpha", Strong.easeOut, imageLoader.alpha, 1, 2, true);
    //fadeOut();
    myTween.addEventListener(TweenEvent.MOTION_FINISH, TimerIgnite);
function TimerIgnite(e:Event):void{
    delay.start();
    delay.addEventListener(TimerEvent.TIMER, nextImgF);
    //fadeOut();
function checkerF(event:TimerEvent):void{
    if(imgNum == 0){
        packagedF();
    }else if(imgNum < numberOfChildren){
//        fadeOut();
        //imageLoader.unload();
        packagedF();
    }else{
//        fadeOut();
        //imageLoader.unload();
        imgNum = 0;
        packagedF();
function nextImgF(e:Event): void {
    delay.stop();
    checkSec.addEventListener(TimerEvent.TIMER, checkerF);
    //fadeOut();
    imgNum++;
function fadeOut():void{
    delay.stop();
    imageLoader.alpha = 0;

Answer 1

OK, the error was coming from me not putting the master_mc in.  clbeech posted that while I was typing in my response. (thank you)
Once I put that in, the error went away and the code sort of works.  It will dump the image but not immediately.  There is a real delay on the doOldLoader leaving the stage. I have the removeChild as the first thing in the TimerIgnite function so where is there a delay coming from?
Here's the code:
import fl.transitions.Tween;
import fl.transitions.easing.*;
import fl.transitions.TweenEvent;
var myTween:Tween;
var xmlRequest:URLRequest = new URLRequest("imageData.xml");
var xmlLoader:URLLoader = new URLLoader(xmlRequest);
var imgData:XML;
var imageLoader:Loader;
var rawImage:String;
var rawH:String;
var rawW:String;
var imgNum:Number = 0;
var checkSec:Timer = new Timer(100);
var delay:Timer = new Timer(1000);
var numberOfChildren:Number;
var doOldLoader: Loader;
xmlLoader.addEventListener(Event.COMPLETE, xmlLoadedF);
function xmlLoadedF(event:Event):void {
    checkSec.start();
    checkSec.addEventListener(TimerEvent.TIMER, checkerF);
    imgData = new XML(event.target.data);
function packagedF():void{ 
    checkSec.removeEventListener(TimerEvent.TIMER, checkerF);
    rawImage = imgData.image[imgNum].imgURL;
    numberOfChildren = imgData.*.length();
    rawW = imgData.image[imgNum].imgW;
    rawH = imgData.image[imgNum].imgH;
    if ( null != imageLoader )
    doOldLoader = imageLoader ;
        imageLoader = new Loader;
        imageLoader.load(new URLRequest(rawImage));
        master_mc.addChild(imageLoader);
        imageLoader.x = (master_mc.width - Number(rawW)) / 2;
        imageLoader.y = (master_mc.height - Number(rawH)) / 2;
        imageLoader.alpha = 0;
        myTween = new Tween(imageLoader,"alpha", Strong.easeOut, imageLoader.alpha, 1, 2, true);
        myTween.addEventListener(TweenEvent.MOTION_FINISH, TimerIgnite);
function TimerIgnite(e:Event):void{
    if (null != doOldLoader)
        master_mc.removeChild(doOldLoader);
    delay.start();
    delay.addEventListener(TimerEvent.TIMER, nextImgF);
function checkerF(event:TimerEvent):void{
    if(imgNum == 0){
        packagedF();
    }else if(imgNum < numberOfChildren){
        packagedF();
    }else{
        imgNum = 0;
        packagedF();
function nextImgF(e:Event): void {
    delay.stop();
    checkSec.addEventListener(TimerEvent.TIMER, checkerF);
    imgNum++;