Preloader that loads 50% then plays

programming flash
1

I want to make a preloader that begins my flash movie once it has 25% or 50% of the swf loaded. This is what I have on my first frame of my preloader right now:
bytes_loaded = Math.round(this.getBytesLoaded());
bytes_total = Math.round(this.getBytesTotal());
getPercent = bytes_loaded/bytes_total;
loadBar_mc._height = getPercent179;
this.loadText = Math.round(getPercent100);
if (bytes_loaded == bytes_total) {
this.gotoAndPlay(3);
}

This works fine and dandy.

I’ve tried:
bytes_loaded = Math.round(this.getBytesLoaded());
bytes_total = Math.round(this.getBytesTotal()/2);
getPercent = bytes_loaded/bytes_total;
loadBar_mc._height = getPercent179;
this.loadText = Math.round(getPercent100);
if (bytes_loaded == bytes_total) {
this.gotoAndPlay(3);
}

and I’m getting errors.

Can anyone help??