Need preloader goto at 50 percent

I’m using a preloader with graphic load bar and percent text with the below script (found on this great site!). I have a large flash movie and I’d like to go to frame 3 at 50 percent bytes loaded (while the rest loads in background). I’ve tried a number of variables for 50 percent, but load bar continues to load and stops at frame 2. I’m new to flash script, any help would be greatly appreciated.

bytes_loaded = Math.round(this.getBytesLoaded());
bytes_total = Math.round(this.getBytesTotal());
getPercent = bytes_loaded/bytes_total;
this.loadBar._width = getPercent200;
this.loadText = Math.round(getPercent
100)+"%";
if (bytes_loaded == bytes_total) {
this.gotoAndPlay(3);
}

Using Flash MX Version 6.
Thank you very much.