Strange roblems with sessions

what it is meant to do: take a querystring set it to a session variable (outputs error if neither querystring nor sesison exist) then reloads the page (to remove the querystring) what it (appears) to do: it sets the querysting to the session, reloads the page and outputs an error saying it doesn't have the session variable if you reload the page with a querystring back in and it works as it is meant to <------ the code in question --------> <? session_start(); if(!isset($_SESSION['HID']) && !isset($_SERVER['QUERY_STRING'])) die("There was an error registering your product please call techinal support at (111)-111-1111"); else if(!isset($_SESSION['HID']) && isset($_SERVER['QUERY_STRING'])) { $_SESSION['HID'] = $_SERVER['QUERY_STRING']; header("Location: http://localhost/PHP/registration_form.php"); } ?> <---------------------------------> I have attached the actual files if that would be of more help, Thanks in advance for any help, ~Logan