[Samba] winbind problem

[Sergiu Dunca]

Hello
I've got a little problem with pam_winbind. My /etc/nssstitch.conf 
contains:

passwd:     files winbind
group:      files winbind

My /etc/pam.d/login contains:
account    required     /lib/security/pam_winbind.so debug

Authentication with pam_smb_auth.so works fine but there seem to be a PAM 
account problem of pam_winbind: I've got the following message:

pam_winbind[3590]: user `admin' not found.

Do I have to make some extra-configs to pam_winbind to work ?

Thanks for any help,
Sergiu