Loading text with progress

1

when i simulate download
this code will not work it just gives 100% when its compleate
any idea how to load text with progress

var loader = new URLLoader();
loader.load(new URLRequest("sometext.txt"));
loader.addEventListener(ProgressEvent.PROGRESS, progressHandler);
function progressHandler(event:ProgressEvent):void {
txt.text = (event.bytesLoaded / event.bytesTotal)*100+"%"
}