This code works correctly with the loading bar, however, my game isn't working correctly once loaded. The standalone swf for the game itself plays fine, just not when it is played through the loader's swf. I get this:

TypeError: Error #1009: Cannot access a property or method of a null object reference.
at MainGame/startGameLevel()
at MainGame/frame2()

The game screen loads, objects animate, but character controls are unresponsive. Anyone know how to fix this?

Code:
var myLoader:Loader = new Loader();
var myRequest:URLRequest = new URLRequest("MainGame.swf");
myLoader.load(myRequest);

myLoader.contentLoaderInfo.addEventListener(ProgressEvent.PROGRESS,showProgress);
myLoader.contentLoaderInfo.addEventListener(Event.COMPLETE,showLoadResult);

function showProgress(evt:ProgressEvent):void {
	var toLoad:Number = evt.bytesTotal;
	var loaded:Number = evt.bytesLoaded;
	var total:Number = loaded/toLoad;
	
	preloader_mc.preloaderFill_mc.scaleX = total;
	preloader_mc.percent_txt.text = Math.floor(total*100) + "%";
	preloader_mc.ofBytes_txt.text = loaded + "bytes";
	preloader_mc.totalBytes_txt.text = toLoad + "bytes";
}

function showLoadResult(evt:Event):void {
	removeChild(preloader_mc);
	addChild(myLoader);
}