[Samba] net rpc group error

[Kurt De Kesel]

Hello,

I receive this error when trying to add an Active Directory user in the Backup 
Operators group.
Do you know what could be the reason and how to fix it ?

The server dali is a  sun solaris system:

SunOS dali 5.9 Generic_118558-05 sun4u sparc SUNW,Sun-Fire-480R
The samba version on this server is 3.0.9
This server is succesfully joined into the active directory domain EMEA

net rpc info -S dali
Domain Name: EMEA
Domain SID: S-1-5-21-2188191474-962303098-1574304029
Sequence number: 1197369746
Num users: 0
Num domain groups: 0
Num local groups: 0

net rpc group list -Uadminbbs
Password:

System Operators
Replicators
Guests
Power Users
Print Operators
Administrators
Account Operators
Backup Operators
Users

net groupmap list
System Operators (S-1-5-32-549) -> -1
Replicators (S-1-5-32-552) -> -1
Guests (S-1-5-32-546) -> -1
Domain Admins (S-1-5-21-2188191474-962303098-1574304029-512) -> -1
Domain Guests (S-1-5-21-2188191474-962303098-1574304029-514) -> -1
Domain Users (S-1-5-21-2188191474-962303098-1574304029-513) -> -1
Power Users (S-1-5-32-547) -> -1
Print Operators (S-1-5-32-550) -> -1
Administrators (S-1-5-32-544) -> -1
Account Operators (S-1-5-32-548) -> -1
Backup Operators (S-1-5-32-551) -> -1
Users (S-1-5-32-545) -> -1

net rpc group addmem "Backup Operators" adminbbs -Uadminbbs
Password:

Could not lookup up group member adminbbs
Could not add adminbbs to Backup Operators: NT_STATUS_NONE_MAPPED