i'd been looking for a while and not seen this as a solution - you might like to try it.
i'm certain i followed the instructions correctly, but having logged out and in again and not having seen a super admin ( only admin ) button i did it all again.
i started with a clean database and clean installation on a sub-folder of another site. cleared cookies b4 logins.
although there was no superadmin button i went directly to /wp-admin/network/sites.php and from then onwards the user 'admin' was given SuperAdmin rights and i had access to all that comes with that.