[Mailman-Users] 2.1.13 install dir permissions

[me at electronico.nc]

Hello everyone,

Please excuse-me for this question but I haven't been able to find the 
answer in archives ...
I try to install 2.1.13 on a new server.
(2.6.28-18-server #59-Ubuntu SMP Thu Jan 28 02:23:52 UTC 2010 i686 
GNU/Linux)

I have used the --prefix option to install mailman in a different 
directory :
./configure --prefix=/home/mailman

I can't (and make install neither) mkdir in choosen directory.

Here are the permissions for /home/mailman :
drwxrwsr-x  2 mailman mailman 4,0K 2010-02-08 08:18 mailman

Here are the groups for the user 'serveur' (the one I launch make 
install from) :
id serveur
uid=1000(serveur) gid=1000(serveur) 
groupes=1000(serveur),4(adm),20(dialout),24(cdrom),46(plugdev),116(lpadmin),117(sambashare),118(admin),20006(mailman)

Thanks in advance for your help.