Deleting Cookies

[sake]

Hey Everyone:
I dunno if it's just really late and i cant see the blatantly obvious error right in front of me, or there's something im doing thats completely out of my knowledge. Anyway, i ask you, is there anything wrong with this block of code:
[php]
if(isset($_COOKIE['lastMob'])){
$lastMob = $_COOKIE['lastMob'];
print "Cookie was set to: ".$_COOKIE['lastMob']."<br />";
setcookie("lastMob", "", time()-3600);
}else{
$lastMob = rand()%$numrows;
setcookie('lastMob',$lastMob);
print "Cookie was not set... setting cookie to ".$lastMob."<br />";
}
[/php]
Correct me if Im wrong: setcookie("lastMob", "", time()-3600) should kill the cookie right? Everytime i run this code the cookie never dies. it just sits there taunting me. What's wrong with my code?

[stepterr]

This is what I use and it works like a charm. I have two cookies, "ID_my_site" and "Key_my_site".


[PHP]
<?php
$past = time() - 100;
//this makes the time in the past to destroy the cookie
setcookie(ID_my_site, gone, $past);
setcookie(Key_my_site, gone, $past);
header("Location: login.php");
?>[/PHP]