MovieClipLoader and checking whether clip was previously loaded

Hi,

I'm using a preloader and MovieClipLoader to seemingly good effect and I have an ending sequence to my preloader where it plays out once the target clip is loaded. The ending sequence features within the preloader itself (preloader_mc.endingClip). preloader_mc plays through its frames with:

function onLoadProgress(target, loadedBytes, totalBytes){
target.stop();
target._visible = false;
var StepUpBytes = totalBytes/100;
stepFrame = Math.floor(loadedBytes/StepUpBytes);
if(stepFrame<1){
  stepFrame = 1;
}
preloader_mc.gotoAndStop(stepFrame+1); 
}

until it gets to 100% and then gets to a frame telling endingClip to play. All good unless the target clip is already loaded. Then what happens is that the preloader jumps to 100% and only plays the ending sequence. I would like to have a way of checking to see if the target clip has already been loaded so as to avoid displaying only this ending portion of the preloader.

In onLoadProgress I tried:

if((loadedBytes == totalBytes) && (target._width > 0)){
  preloader_mc.removeMovieClip();
}

This isn't working but I'm confused because for each of my targets I have an empty clip and when a new one is loaded, the current one is made _visible = false. I therefore thought the (target._width > 0) bit would work since the empty clip would already house the target? Trace returns zero for width value and returns different values for loadedBytes and totalBytes even if I revisit a freshly loaded clip.

The loadClip is triggered by an onPress event as described here:

navMenu.navClip.Section3But.onPress = function  () {
startPreload("flash/construction.swf");
function startPreload(url){
  loader_mcl.loadClip(url, ConstructionClip);
    }
this.enabled = false;
onEnterFrame = function (){
  PropDevClip._visible=false;
  ProjManClip._visible=false;
  DesignClip._visible=false;
  delete onEnterFrame;
}