Issue with nav buttons in an image gallery

Question

Hello,
I'm very new to flash and am using CS4/AS3. I have three image galleries of three images each. The images load dynamically from files on my computer. I've set it up so that when you click on a tab, you see a different set of three images.
The images load properly and it works to click forward to view them (that is, clicking on the image itself or the forward nav arrow). The issue I'm having is with the backward nav arrow. I keep geting an error message "Error #2044: Unhandled IOErrorEvent:. text=Error #2035: URL Not Found" when I click it.
The backward nav arrow works on the first gallery (egypt gallery) if I click that one first. But it doesn't work on the other two, and if I click back to the Egypt gallery after having been in the other two galleries, the back navigation no longer works in their either.
Basically, I want the user to be able to click on a tab to load the images, and then be able to click back and forth between the images. If they reach the last image in a gallery, I just want it to stop advancing and stay put on the final image, but for the user to be able to click backwards through them if desired. My code is pasted below (I'm sure it's more complicated than it needs to be... just a result of me being a complete novice!)
Any help or suggestions would be very much appreciated. Thanks so much.
stop();
//egypt gallery//
var myloader:Loader = new Loader();
var myrequest:URLRequest = new URLRequest("images1/egypt1.jpg")
var counter:Number=1
var total:int=3;
egypt_mc.addEventListener(MouseEvent.CLICK, cover);
function cover (e:MouseEvent):void{
object1_mc.x=414.15;
object1_mc.y=101.35;
object2_mc.x=520;
object2_mc.y=60;
object3_mc.x=630;
object3_mc.y=60;
left_mc.x=15;
left_mc.y=340;
right_mc.x=680;
right_mc.y=340;
stage.addChild(myloader);
myloader.x = 28;
myloader.y = 175;
myloader.load(myrequest);
myloader2.unload();
myloader3.unload();
myloader.addEventListener(MouseEvent.CLICK, shownextpicture)
function shownextpicture(e:MouseEvent):void{
counter = counter + 1;
if(counter<=total){
myrequest.url="images1/egypt"+counter+".jpg"
myloader.load(myrequest)
right_mc.addEventListener(MouseEvent.CLICK, forward)
function forward(e:MouseEvent):void{
counter = counter + 1;
if(counter<=total){
myrequest.url="images1/egypt"+counter+".jpg"
myloader.load(myrequest)
left_mc.addEventListener(MouseEvent.CLICK, back)
function back(e:MouseEvent):void{
counter = counter - 1;
if(counter>0){
myrequest.url="images1/egypt"+counter+".jpg"
myloader.load(myrequest)
//wikileaks gallery//
var myloader2:Loader = new Loader();
var myrequest2:URLRequest = new URLRequest("images2/wikileaks4.jpg")
var counter2:Number=4
var total2:int=6;
wiki_mc.addEventListener(MouseEvent.CLICK, cover2);
function cover2 (e:MouseEvent):void{
object1_mc.x=410;
object1_mc.y=60;
object2_mc.x=521.35;
object2_mc.y=102;
object3_mc.x=630;
object3_mc.y=60;
left2_mc.x=15;
left2_mc.y=340;
right2_mc.x=680;
right2_mc.y=340;
stage.addChild(myloader2);
myloader2.x = 28;
myloader2.y = 175;
myloader2.load(myrequest2);
myloader.unload();
myloader2.unload();
myloader2.addEventListener(MouseEvent.CLICK, shownextpicture2)
function shownextpicture2(e:MouseEvent):void{
counter2 = counter2 + 1;
if(counter2<=total2){
myrequest2.url="images2/wikileaks"+counter2+".jpg"
myloader2.load(myrequest2)
right2_mc.addEventListener(MouseEvent.CLICK, forward2)
function forward2(e:MouseEvent):void{
counter2 = counter2 + 1;
if(counter2<=total2){
myrequest2.url="images2/wikileaks"+counter2+".jpg"
myloader2.load(myrequest2)
left2_mc.addEventListener(MouseEvent.CLICK, back2)
function back2(e:MouseEvent):void{
counter2 = counter2 - 1;
if(counter2>4){
myrequest.url="images2/wikileaks"+counter2+".jpg"
myloader2.load(myrequest2)
//scientology gallery//
var myloader3:Loader = new Loader();
var myrequest3:URLRequest = new URLRequest("images3/scientology7.jpg")
var counter3:Number=7
var total3:int=9;
scien_mc.addEventListener(MouseEvent.CLICK, cover3);
function cover3 (e:MouseEvent):void{
object1_mc.x=410;
object1_mc.y=60;
object2_mc.x=520;
object2_mc.y=60;
object3_mc.x=629.95;
object3_mc.y=100.8;
left3_mc.x=15;
left3_mc.y=340;
right3_mc.x=680;
right3_mc.y=340;
stage.addChild(myloader3);
myloader3.x = 28;
myloader3.y = 175;
myloader3.load(myrequest3);
myloader.unload();
myloader2.unload();
myloader3.addEventListener(MouseEvent.CLICK, shownextpicture3)
function shownextpicture3(e:MouseEvent):void{
counter3 = counter3 + 1;
if(counter3<=total3){
myrequest3.url="images3/scientology"+counter3+".jpg"
myloader3.load(myrequest3)
right3_mc.addEventListener(MouseEvent.CLICK, forward3)
function forward3(e:MouseEvent):void{
counter3 = counter3 + 1;
if(counter3<=total3){
myrequest3.url="images3/scientology"+counter3+".jpg"
myloader3.load(myrequest3)
left_mc.addEventListener(MouseEvent.CLICK, back3)
function back3(e:MouseEvent):void{
counter = counter - 1;
if(counter>0){
myrequest.url="images3/scientology"+counter+".jpg"
myloader.load(myrequest)

Answer 1

You want to have the trace triggered when the problem occurs, so if the problem occurs when you use your back button, then you want to tie it in to that somehow.  I don't know why you are trying to trace all that you show.  The main thing you want to find out is why it is not finding the file, which will be defined by whatever value it is trying to use as a url.  Try to focus on the data you need to see and not just anything that comes to mind.