This.tage and this.parent property null

Hi everyone,
I try to call a function from a parent swf as I do normally by calling the parent function as follow:
if(this.parent!=this.stage){
m_xml = (Object)(this.parent).GetXML();
}
else{
m_xml = …
}
I did that in all my old project and it work find but now when i export it on the web, there always a error saying that the this.parent and this.stage is null so it can call the function.
this.parent and this.stage work perfectly when i am local cause i don’t load the swf from the main swf but as soon as the swf is load from the main swf on the web, this.parent and this.stage as this itself, as no more property as it should be. I really don’t understand what happen here. Sorry for my english.
this is what i import :
import flash.system.LoaderContext;
import flash.display.Loader;
import flash.display.AVM1Movie;
import flash.display.Sprite;
import flash.display.MovieClip;
import flash.xml.;
import flash.display.MovieClip;
import flash.text.TextField;
import flash.events.
;
import flash.net.URLLoader;
import flash.net.URLRequest;
import flash.net.URLLoaderDataFormat;
import flash.utils.Timer;
import fl.transitions.Tween;
import fl.transitions.easing.*;
import fl.transitions.TweenEvent;
import flash.net.navigateToURL;
import flash.system.System;
is there is something i do wrong here?