I received two emails that my membership is approved, still I am not a member of the group. Why ?

I received two emails that my membership is approved (one from the group moderator and the other from notify@yahoogroups.com), still I am not a member of the group. When I visit the "my groups" page, the group doesn't appear and when I visit the group page I can't enter the "members only" area and the "Join this group" on is still there. Why ?