setcookie problem

I've reached a problem which I don't know how to get over it. Consider you have a PHP page with the following address: http://www.domain.com/users/signin/set.php this script's job is to set a cookie and it does. The problem is when I set them, when some other pages want to use that cookie, only the scripts which are in the same folder (with the script that set the cookies) can reach them and for other scripts it's hidden. How can I set a cookie that all the pages can access it. I'm setting the cookie with the following script: setcookie("SessionID", $SessionID, 0, "/"); and if it helps I'm using IE6 thanks,