[Mailman-Users] gid problem

[Minitom]

Hello,

first I would like to thank the people who replied to my first post to this list.

Now ... my problem :

I compiled mailman with options : ./configure --with-mail-gid=12 --with-cgi-gid=48. Of course 12 is for "mail" and 48 is for apache. I add a new list : everything is OK. I add a user to the list : evrything is OK. But when the user try to confirm the subscription, I get the same reply than before, but whith a whole new error message.

I'm sure the list exists (I can read the right lines in /etc/postfix/aliases), but this is the message users get :

I'm sorry to have to inform you that the message returned
below could not be delivered to one or more destinations.
For further assistance, please send mail to <postmaster>
If you do so, please include this problem report. You can
delete your own text from the message returned below.
              The Postfix program
<test-request at blaster.dyndns.org>: Command died with status 2:
   "/home/mailman/mail/wrapper mailcmd test". Command output: Failure to exec
   script. WANTED gid 12, GOT gid 99.  (Reconfigure to take 99?)

??? 99 is the "nobody" account. Did I forget any option when I ran ./configure ? 

Thanks for your help