chmod - Opertaion not permitted in ....

[Morris <morris520@xxxxxxxxx>]

Hi all
Got a problem don't know how to get in really..

simple code:
<?php

chmod("/aaa/bbb.php", 0777);

?>

and I get a warning says "Operations not permitted in ....."

Anyone met this before? I've done quite a lot reading on Google but couldn't
get to it.

THanks