code works when published and in web page but not in folder view

I am trying to run this code in a button function:

hilite2_mc.addEventListener(MouseEvent.MOUSE_DOWN, playhilite2);

function playhilite2(event:MouseEvent):void
{
hilite2_mc.play();
ExternalInterface.call("parent.doNextStep");

nextFrame();
}

nextFrame works when I publish and in the webpage, but if I click on it in a folder it does not work. I can put nextFrame above the External code and then it works fine, but I would rather not do that...

Thanks in advance