UILoader preloader problem

programming flash
1

this is how it works. i add gallery mc to stage by this code:

var galleryPage = new pageGallery();
galleryPage.stop();
gallery_mc.addEventListener(MouseEvent.CLICK, btnClick);
gallery_mc.targetMc = galleryPage;

function btnClick(e:MouseEvent):void
{...
addChild(currentPage.targetMc);
currentPage.targetMc.gotoAndPlay(1);
..}

inside galeryPage there is UIloader added to stage with parameters set to load an external file - gallery.swf.

here is UILoader event code(its written at galleryPage frame):

stop();

myLoader.addEventListener(Event.COMPLETE, fadeIn);

function fadeIn(e:Event):void
{
    trace("loaded");
    preloader_mc.alpha=0;
    new Tween(myLoader,"alpha",Strong.easeOut,0,1,1,true);
}

testing movie traces “loaded” straight away just afer comilation is finished. when i go to the galeryPage preloader_mc is already set to alpha=0;
why is the event completed so early and not after going to the galleryPage? how to make it work?