HTTP_REFERER is empty!

[Anon]

i try to put the code like this:

<?php

echo $HTTP_REFERER;
$refer = getenv("HTTP_REFERER");
echo $refer;

?>

i don't know why those 2 variables are empty. (Echo blank).
I worked on Win2k with Apache for win32 and PHP 4.0.3 (cgi).

How can i solve this.
Thanks in advance.

[Anon]

write a page that links to that page. click the link. then it will not be empty.