Externally loaded .swf positioning problem

1

So, basically, I’ve loaded an .swf into an empty movie clip in my movie and positioned it with this code:

var lp:Object = new Object();
lp.onResize = function() {
        loop_mc._y = Stage.height-275;
        loop_mc._x = (Stage.width-800)/2;
                  }
Stage.addListener(lp);
    lp.onResize();

When I hit cntrl + enter, everything lines up looks good and works fine. When I do a publish preview in HTML however, the mc is dragged all the way to the bottom of my screen and mostly hidden beneath my footer. Any ideas on what could be causing this? Any help is greatly appreciated, thanks.