[Samba] Group mapping, net group add troubles !!!

[Ganael LAPLANCHE]

Hi all,

I'm trying to add a Unix group to Samba to test group mapping...

At the beginning, I just wanted to map the Windows Domain Admins group to
my Linux group, called domainadmins :
"net getlocalsid", then
"net groupmap add sid=<SID>-512 unixgroup=domainadmins"
But here is what Samba returns : Group 1004 must exist exactly once in LDAP

Okay, no pb, I just have to create the domainadmins group under Samba (into
my LDAP directory), so :
"net group ADD domainadmins -U smbadmin"
(smbadmin is a Linux AND Samba user with uid/gid 0)
Unfortunately, Samba returns this error message : return code = 50
Don't know what it means, but the group isn't added, if I try to list Samba
groups :
"net group -l -U smbadmin"
The list is empty :((

Could someone help me with adding new (Unix-already-existing) group to
Samba ?
How could I map this group to the M$ "Domain admins" one ?

Thank you very much !

Ganaël LAPLANCHE.