Event Back-End Admin: How to add a Guest?

I'm trying to add a user to an event as a guest via the back-end admin screen. Can this be done?

There are 'Invite Guests' and 'Approve Guests' button... I invited a person and then tried to 'approve' him with the 'approve guests' button but it doesn't seem to have any affect.

Should there be a 'Add Guests' button here.. or if not, how does 'Approve Guests' work?