private groups

I created a "strictly" private group on my commons installation and prevented the group to be listed on the front page. Members were added to the group by the group manager. However, members cannot see the group listed on their front page, nor is it appearing in the "My Stuff>>My groups" or in the "Community>>Groups" pages. In other words, the group is completely invisible to everyone, including its own members. How can I make it visible to members and invisible to everyone else?