Verified answer

Try not to list the group in Yahoo! directory as you've created your new group by customizing it.

If you want to make yours a private group,

type the exact name of your group instead of the XXX:

http://groups.yahoo.com/group/XXX/settings?mode=10

Edit the Listing Type / Save the Change.

Hope that helps!

You can always remove your group from the directory in management.

All member have to be approved, in case outsiders wander in