自定义会话ID未被记住

Question

I'm creating a script with sessions but the server doesn't remember the settings. It's using a variable id so that might be the problem but how can I fix this?

Here is the code:

URL Example: http://domain.eu/isloggedin.php?code={0} <- Windows Application will fill this in.

Login:

<?php
ini_set("display_errors", 1);
error_reporting(E_ALL);

session_start();
$code = $_GET['code'];
$lstring = $code . "-CONFIG";
$_SESSION[$lstring] = "True";
?>

GET:

<?php
ini_set("display_errors", 1);
error_reporting(E_ALL);

session_start();
$code = $_GET['code'];
$lstring = $code . "-CONFIG";
if (isset($_SESSION[$lstring])){
echo "True";
}

What am I doing wrong??

Regards,

Daniël