Hi dude,
I am not really sure which session handling functions you have used. So, I can't pin point a solution to you. Morover, I haven't worked in PHP for some time now.

If you haven't checked already, it is worth checking the PHP documentation which is really great. Here is the link to the session related functions documentation.

http://www.php.net/session

Hope this helps. Sorry dude, couldn't be too specific.

Cheers!
Kalayama