Professional :: External Image Loading Into MovieClip On Stage

I am trying to load an external .swf (actually it is only an image that I published as a swf file, not a complicated movie) but I get errors. I am trying to load the .swf into a movieclip and the movieclip appears on the stage. I have put the code in frame 1 where the image should appear (in the movieclip). The code that I used is below and works fine with a .jpg and when I load it directly on the stage, that is to say, when I put the code in a frame on the stage. Why does it not 'work' right now?

I have added 'parent' in 'parent.event.target.content.y = 200;' in the first frame of the movieclip timeline, to make sure that it will appear on the (main)stage. The error that i get is this one:
TypeError: Error #1009: Cannot access a property or method of a null object reference.
at galerie2010_fla::mcBallon1_11/frame1()

This is the code in frame 1 in mcBallon1:
var imageRequest1a:URLRequest = new URLRequest("images/SWFoverig/ballon1_702x368.swf");
var imageLoader1a:Loader = new Loader();
imageLoader1a.load(imageRequest1a);
addChild(imageLoader1a);
imageLoader1a.contentLoaderInfo.addEventListener(Event.COMPLETE, onComplete1a);
function onComplete1a(event:Event):void{
parent.event.target.content.y = 200;
parent.event.target.content.x = 205;}