[lava session] urgent help plzz !!

[12345xmen]

i make my lava secure via this way

add in all file at the top

session_name("PHPSESSID");
session_start();


and chnage this to

$sid = $_GET["sid"];

this

$sid = $_SESSION['sid'];


and remove all this tag

&sid=$sid from all link .

but when i login its say session expir wht i do ???????