Problems with preloader

1

Hi!..I got a problem with a preloader… doesn’t show from the beginning…just when the .swf is about to load. This is the code:

var root:MovieClip = this;
root.onEnterFrame = function() {
tot = root.getBytesTotal();
car = root.getBytesLoaded();
por = Math.round((car*100/tot));
textoPrecarga.text = “Cargando… “+por+”%”;
barra._xscale = por;
if (tot == car && car>0) {
delete root.onEnterFrame;
}
};

It just happens with some .swf files… and I don’t know if it is to do with the structure of these 'cause there are buttons with load movieclips …eg:

on(release) {
picture.attachMovie(“alum3”, “loadedMovie”, 2);

}