then turn errors on & see why it's not echoing the value
ini_set('display_errors', 1);
error_reporting(E_ALL);
my money's on it not being defined, as what you have (in addition to the missing semi-colon) is correct.
(and you do mean $session right? not $_SESSION)
...oh this is something I just figured out today on my server, /folder/file.php doesn't work, only folder/file.php works, maybe its the first backslash in your include?