Loading an external sound with progress

1

hi this works when I test it on my computer. But when I put it online, the bytes progress becomes undefinable / NaN… I don’t know why being online makes a difference…
well, here’s the code if anyone can help?

function loading()
{
    maskWidth = 230/100;
    var trackTotal:Number = sound.getBytesTotal(obj);
    var trackNow:Number = sound.getBytesLoaded(obj);
    var percent:Number = (trackNow/trackTotal)*100;
    var Total:Number = maskWidth * percent
    loading_mask._width = Total;
    bytes.text = Total;
    if(Total >= 100)
    {
        delete this.onEnterFrame;
    }
}
var sound:Sound = new Sound(obj);
function playTrack(track)
{
    sound.loadSound(track,true);
    loading_mask.onEnterFrame = loading;
}

ta!