the loader.fla file uses a UILoader, so there is no code. I created another file using object loader. That file uses this:
var swfLoader:Loader = new Loader();
var swfFile:URLRequest = new URLRequest("step_1.swf");
var container:MovieClip= new MovieClip();
swfLoader.load(swfFile);
container.addChild(swfLoader);
addChild(container);
That also fails. The traces are:
[object Loader]
[object MovieClip]
instance2
TypeError: Error #1034: Type Coercion failed: cannot convert flash.display::Loader@7fff9c15ea1 to flash.display.MovieClip.
at step_1_fla::MainTimeline/frame2()
you must be changing your code to cause different error messages and that's making it difficult to help you.
if you leave the code in message 16, use:
MovieClip(this.parent.parent.parent).gotoAndStop(2)
in the loaded swf.