Setting Interval, not working externally

Hello, my code looks like this:

function playit(){
   _root.gotoAndPlay(4);
}
setInterval(playit, 58900);

It works nice when i play the movie, but when i load it from my main movie it doesnt works (obvious, “_main” changes to be the movie that is loading). Now, i used “_parent” but it doesnt work, “this” neither; so, thats my problem, when i load the movie with this code inside, into another movie it won’t work. =(