What's wrong with this target path?

1

nothing is happening when i click the thumbnails that are being loaded from xml into an attached movie. this has got to be a really easy answer here. any ideas?

 
 
for (var z = 0; z < articleNos; z++){ // start looping through xml
   var item_mc = thumb_list.attachMovie("indiv_thumbs","indiv_thumbs"+item_count, item_count, {_x:5, _y:0});
   item_mc._y = item_count * item_spacing;
   item_count++;
   item_mc.loadMovie(seasArts.firstChild.childNodes[z].childNodes[5].firstChild.nodeValue,5);
 
   }// end for xml loop
 
   item_mc.thumb_list["indiv_thumbs"+item_count].onRelease = function(){
    //if(i < articleNos){
     //i = i+1;
    //} else {
     trace("Hello");
     _root.art_count = "5";
   }

thanks!