Referer problem

Hi there, I am trying to prevent hotlinking of images by other servers. Pictures are generated on the fly by a php script, where I have included this code to prevent hot linking: $haystack = $_SERVER['HTTP_REFERER']; $needle = 'globosapiens';

$pos      = strpos($haystack, $needle);

if ($pos === false) { // not from globosapiens HEADER("Location:/g/p/2/hotlink_banner.gif"); exit; } It workes, but not for everybody. Some user tell me that they see the hotlink_banner.gif on my website as well. How is this possible? Has anybody an idea on where the error is, and how to fix it?` Thank you in advance, Merlin