Halfway preloader

Hi,
my preloader plays about halfway and then begins the movie even though the movie is still downloading. Would it have anything to do with the streaming audio or because the file is big? Any help will be appreciated.

onClipEvent (enterFrame) {
bytes_loaded = Math.round(_root.getBytesLoaded()/1000);
bytes_total = Math.round(_root.getBytesTotal()/1000);
getPercent = bytes_loaded/bytes_total;
this.loadBar._width = getPercent100;
this.loadKb = “Loading “+bytes_loaded+” Kb of “+bytes_total+” Kb”;
this.loadText = Math.round(getPercent
1000);
if (bytes_loaded == bytes_total) {
_root.play();
}
}