noob need help for sessions

I'm having problem with my session, when I login my session is registered ok but when I click on another page it's canceled again. I use that kind of link: index.php?menu=voyage&sid=$sess_id then on top of the page I use: if(session_id()){ session_id(strip_tags($_GET['sid'])); session_start(); $sess_id = session_id(); $nom_user = $_SESSION['session_nom']; $prenom_user = $_SESSION['session_prenom']; $bienvenue="Bienvenue $prenom_user $nom_user"; } http://81.57.4.105/~pat/alliance/ (user and pass = admin) can someone tell me how when I click on the top boxes link the session is not kept? here is the code: http://hashphp.org/pastebin?pid=2354 thanx in advance Pat