setInterval, Firefox vs IE

Hi, I am learning flash and trying to make my own photo gallery. I thought that I had everything working, but that was because I was testing my script with Firefox…

The problem:
I use a setInterval to show the progress bar when I load a photograph. In Firefox, the % grows until it reaches 100%, and then the loader dissapears. In IE, my loader allways shows 0%, even after the photo loaded… I searched in google and in the forums, but I cant find any similar problem. Can you help me out?

This is my code:

When I change the contentPath of my loader, I run this:
loadPhotoInterval = setInterval(photograph.loadPhoto, 100);

Inside photograph movieclip I have this code:

function loadPhoto() {
if (photo.getBytesTotal() != 0) {
photoloader_mc._visible = true;
photo_percent = Math.round(photo.getBytesLoaded() / photo.getBytesTotal() * 100);
photoloader_mc.percent = photo_percent + “% cargado”;
if (photo_percent == 100) {
photoloader_mc._visible = false;
clearInterval(loadPhotoInterval);
} else {
photoloader_mc._visible = true;
}
}
}

You can see it in action here:
http://www.pmarin.com.ar/fotos/galeria.html?id=300&seccion=galerias