.swf on another .swf

Hey guys!

I have menu with a transparent background. I also have a swf where two images are fading towards each other. Both are on the same htmlpage and the menu (when clicked) should popup over the other swf. How do I change what goes on top? I’ve tryed to modify my z-index in my divs but that dosent do the trick. What decides which one of my two .swfs that goes on top and how do i modify it? thanks in advance /Gustav