PHP Image Thumbnail Problem

I'm using a code that displays images from a directory and turns them into thumbnails. In the code:

  if ($image_format==1) {
  $old_image=imagecreatefromgif($filename);
 } elseif ($image_format==2) {
  $old_image=imagecreatefromjpeg($filename);
 } elseif ($image_format==3) {
  $old_image=imagecreatefrompng($filename);
 } else {
  exit;
 }

Code (markup):

the "imagecreatefrompng" isn't working, as only JPGs and GIF's show on the list. Any ideas on how to fix this?

 

do'h. I changed:

if ($ext!='gif' && $ext!='jpg') continue;

Code (markup):

to:

if ($ext!='gif' && $ext!='jpg' && $ext!='png') continue;

Code (markup):

and that did the trick.