[Mailman-Users] Error using mailman

[Soporte]

Hi! I do really need help. When I try to access
httpd://mydomain/mailman/admin/create or any other from mailman the
error is:
 

Mailman CGI error!!!

The Mailman CGI wrapper encountered a fatal error. This entry is being
stored in your syslog: 
Failure to find group name nobody.  Try adding this group

to your system, or re-run configure, providing an

existing group name with the command line option --with-cgi-gid.
 
But the group nobody really exists in /etc/group :
nobody:x:99:
So, what could I do?
Please Help Me!