Confused about $_SESSION and $_COOKIE scope..

I'm not sure why this isn't working, been banging my head at it for a couple hours now. I have a file (index.php), which calls a function that draws the header to my page. Inside that function (site_header), is an include to a file (menu.php) which draws dynamic javascript menus based on cookie or session values. I can't seem to access ANY variables, be them $_SESSION, $_COOKIE, or anything else, inside this menu.php file. I've tried even passing simple variables, globalizing them, etc, all the way down to see if I can access them in that menu.php file. I still can't.. the closest I get is being able to access them in the site_header function, but when the include("menu.php") is called, everything seems to vanish. And yes, I have session_start(); at the top of my menu.php file as well.. Can anyone help me out on this? I was under the impression that the superglobals would be available from basically anything.. apparently I was wrong. Thanks, Chad