Preloader #1009 error

Question

Halo. I've been trying to load external swf  ("index.swf") with the following code in AS3:
//it's a simple preloader with one dynamic text field: "percent"
//the "index.swf" is suppose to stop at 689 frame after being loaded (this part works fine)
stop();
import flash.display.*;
import flash.net.URLRequest;
import flash.events.Event;
var l:Loader = new Loader();
l.contentLoaderInfo.addEventListener(ProgressEvent.PROGRESS, onProgress);
l.contentLoaderInfo.addEventListener(Event.COMPLETE, onComplete);
l.load(new URLRequest("index.swf"));
function onProgress(event:ProgressEvent):void{
   var perc:Number = event.bytesLoaded / event.bytesTotal;
   percent.text = Math.ceil(perc*100).toString();
function onComplete(event:Event):void{
   var container:MovieClip = MovieClip(l.content);
   removeChild(percent);
   percent = null;
   addChild(container);
   container.gotoAndStop(689);
Of course I receive the #1009 error : Cannot access a property or method of a null object reference. I guess it is some "stage issue" but I'm not familiar enought with AS3 to avoid the problem by my own.
Could you please help me with the code.

Answer 1

You were right. My idea about "stage issue" also was confirmed.
The problem was in part of the code on the first frame of the "index.swf" (file that I was trying to load):
stage.align="T";
I think that this part of the code is being executed before the "index.swf" is loaded.
Thanks for replies "kglad" and "Ned Murphy"
Regards