Sound from _root

I want to play some sounds when buttons are rolled over. Its working great thanks to the tutorial on this site. However I am loading swfs externally and now the sounds dont play.
“Contents” is the name of the MC that I am loading external swfs into.
This is how i tried to modify the code so that it plays from the _root, but its not working. Any ideas, any help is great!

_root.contents.mysound = new Sound();
_root.contents.mysound.attachSound("hoverclip");
_root.contents.mysound.start(0,1);

Thanks