preloader script not working in MC

[maydays]

Hi
I have made the next script an put it in the first frame of the stage
it's works fine but if i put it in a MC the progressBar will not work.
Here is the text:

code:

---

stop();

myInterval = setInterval(preloader,10);

function preloader() {

    if (getBytesLoaded() >= getBytesTotal()) {

        play();

        clearInterval(myInterval);

    }

    progressBar._xscale = (getBytesLoaded()/getBytesTotal())*100;

}

---

I have tryed many variation change the play(); with "_root.play",or with "with _root.play..","_root.getbytes..." and so on but i cant make the progressBar work , can someone help me here

Thank you very much..