How to onload an external swf

Hi there

I load an external swf by clicking a button and everything works fine - the problem is that the swf remains after clicking my other buttons. How can I avoid this?
My code looks like this:

on (release) {
this.createEmptyMovieClip("empty_mc",0);
empty_mc._x = 240;
empty_mc._y = 10;
loadMovie("design-swf/designKonceptMenu_v1.swf",empty_mc);
}

Best regards
Jean