Unable to load SWF that works by itself

I have a swf that works just fine and dandy when run by itself, but if I try to load it into a different swf, I get the usual helpful Flash IDE message:

“TypeError: Error #1009: Cannot access a property or method of a null object reference.
at com.playfish.console.widget.external::Main()”

This swf is part of a larger project done in Flex, but it made sense to just do it in the flash IDE. Ok, so this swf is just a collection of movieclips and some code ( even tried to move everything to a separate package, just to ensure it’s not som strange collision between this and parent ). I’m at loss to where the error is, as all that is done in main is instanciating movieclips that are exported in the IDE. And again, this works when I just load up the swf.

This is really annoying, especially since I have no clue what might be causing this. Please just ask if more information is needed, and thanks for any and all help!