_global problems

ok, so i have a main movie that is loading submovies into it in different levels. on my main movie, i have a function called openSubMovie

_global.openSubMovie = function () { // do something }

then in my submovie i have a button that needs to call the function placed above.

so i do something like this

my_btn.onRelease = function () { openSubMovie(parameters); }

my problem is that the function is not being run? could this be because these movies are on different levels? it was my understanding that a global variable can be accessed from anywhere and any timeline? im really confused. I also don’t want to set this function to the _root timeline because then I would have to go and find everywhere I call this function and change it to root and then i would have something hard coded, and I dont like that one bit…