# My app works, but not when I load it into another swf?

**URL:** <https://forum.kirupa.com/t/my-app-works-but-not-when-i-load-it-into-another-swf/306251>\
**Category:** Uncategorized\
**Created:** [March 11, 2010, 7:00pm UTC](https://forum.kirupa.com/t/my-app-works-but-not-when-i-load-it-into-another-swf/306251 "2010-03-11T19:00:50Z")\
**Posts on this page:** 1\
**Page:** 1

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**Author:** ![sabird](https://avatars.discourse-cdn.com/v4/letter/s/aeb1de/32.png) [@sabird](https://forum.kirupa.com/u/sabird)\
**Post date:** [March 11, 2010, 7:00pm UTC](https://forum.kirupa.com/t/my-app-works-but-not-when-i-load-it-into-another-swf/306251/1 "2010-03-11T19:00:50Z")

</div>

I have a map application I’ve built using Flash CS4 and ActionScript 3 .as files. It’s working fine on my local machine. I’m trying to build a preloader for it. My usual way of doing that is to create a shell .swf file which exists just to load the main movie and show the user preloading progress. Unfortunately, whenever I try to load in a movie that uses external .as files, stuff breaks. I’m assuming that it has to do with the LoaderContext and ApplicationDomain, but I’ve tried every ApplicationDomain option, and I always get the same errors.

In my map application, I’ve got a constructor function called Imap() that simply calls an init() function which then sets everything in motion. As I said, when I run the map app, things run smoothly. When I load it into my loader swf, I get (the functions trace out their names as they begin to run):

[FONT=“Courier New”]Imap()  
init()  
TypeError: Error #1009: Cannot access a property or method of a null object reference.  
at com.[domain].imap::Imap/init()  
at com.[domain].imap::Imap()[/FONT]

The code in my (as yet uncompleted) preloader swf is:

[FONT=“Courier New”]package  
{  
import flash.display._;  
import flash.system._;  
import [flash.net](http://flash.net).\*;

public class Preloader extends MovieClip  
{  
var loader:Loader = new Loader();  
var outline:Sprite = new Sprite();  
var fill:Sprite = new Sprite();  
var w:Number = 100;  
var h:Number = 10;  
var loaderContext:LoaderContext = new LoaderContext()  
public function Preloader()  
{  
loaderContext.applicationDomain = new ApplicationDomain();  
// I’ve also tried  
// new ApplicationDomain(ApplicationDomain.currentDomain) ,  
// ApplicationDomain.currentDomain, and  
// new ApplicationDomain(null)  
// all to no effect  
[…]

loader.load(new URLRequest(“map.swf”), loaderContext);  
addChild(loader);

}  
}  
}[/FONT]

This problem has vexed me in the past as well, and I’ve never found a solution for it. If anyone could help me out, that would be great. As an alternative, if anyone would like to suggest a preloading solution that would avoid this whole problem, I would appreciate that as well.

Thanks in advance!