Controlling loaded swf-File

Hi there!

My problem:
I load a movieclip via:

on(release){
loadMovieNum(“detection.swf”, 1);
}

So I load it in my current timeline on level 1. Now in the detection.swf is a button that has to controll the first movie. (that loaded the swf)

I tried:

on(release){
_level0_root.nextScene();
}

which did not work. Referencing via _root.nextScene() also, because the loaded swf has its own _root.

So how can I controll the first movie out of the loaded one?

Kind regards,
philipp