Hiding my back button!

Hey everyone.

Okay so i have a movie clip that holds 20 thunbnails, when i click the thumbs i get a large image that loads into my imageHolder.mc etc.

What im having problems with is i have a “back button” which you can use to go back from the larger image back to the thumbnails. Which all works fine.

But how can it so the back button, only shows up when i have the loaded the larger image? I dont want to see the “next button” on the thumbnails page.

This is the code im using for my images.

goback.onPress = function(){
unloadMovie(“container_mc”);
disableall(true);

}

goback._visable = false;
function disableall(t) {
for (var i = 1; i<numBut; i++) {
this[“image”+i+"_btn"].enabled = t;
}
}

image1_btn.onRelease = function() {
loadMovie(“futbol1.jpg”, “container_mc”);
trans_mc.gotoAndPlay(“transition”);
disableall(false);
}

Any help would save me hour… many thanks

ck