Problem with Session and register_globals

Hello, When I try the code bellow with register_globals=On, it work was expected, the counter variable is incremented each time that I load the page, but, when I try with register_globals=Off, it doesn´t work, the counter variable is incremented just in the first time, the session variable is not update. <?php session_start(); // register a session variable session_register('counter'); $counter = $HTTP_SESSION_VARS["counter"]; // increment and display the value of the counter $counter++; echo("You have visited this page $counter times! Don't you have anything else to do, you bum?!"); ?> How can I fix this?