note 32590 added to function.imagecolortransparent

I have PHP 4.3.1 and when I try to get transparent color from loaded from PNG image with: $res=imagecreatefrompng('foobar.png'); if (!$res) die('Ugly'); $tr = imagecolortransparent($res); print 'TR:'.$tr; I get $tr = -1. My PNG image have for sure big transparent rectangle in the middle. Can somebody explain me what is going on here ? ---- Manual Page -- http://www.php.net/manual/en/function.imagecolortransparent.php Edit Note -- http://master.php.net/manage/user-notes.php?action=edit+32590 Delete Note -- http://master.php.net/manage/user-notes.php?action=delete+32590&report=yes Reject Note -- http://master.php.net/manage/user-notes.php?action=reject+32590&report=yes