samba - Mar 2007 - Samba 3.0.23d-19.2-1179-SUSE-SL10.2 wrong Workgroup listing

Hi list, 

after two days searching for mistake I need some help. The following mistake
happens: 

smbclient -L \\<IP>

Domain=[MYDOMAIN] OS=[Unix] Server=[Samba 3.0.23d-19.2-1179-SUSE-SL10.2]

        Sharename       Type      Comment
        ---------       ----      -------
        IPC$            IPC       IPC Service (Samba server string)
Anonymous login successful
Domain=[MYDOMAIN] OS=[Unix] Server=[Samba 3.0.23d-19.2-1179-SUSE-SL10.2]

        Server               Comment
        ---------            -------

        Workgroup            Master
        ---------            -------
        SERVER1              SERVER1

The listing under Workgroup is wrong and I don't know where's the
mistake.

In this case, nmbd is not able to register the master because SERVER1 is the
hostname, not the Workgroup or Domain. Next, I need to setup samba with
LDAP backend and the registered SambaDomainName is "Server1". 

Heres the minimalized and just for testing written samba.conf:
[global]
    netbios name = Samba bios name
    workgroup = Mydomain
    server string = Samba server string
    security = user
    log level = 10
    max log size = 5000
    local master = yes
    os level = 65
    domain master = no
    preferred master = yes
    domain logons = yes
    logon path = \\%L\profiles\%U
    logon drive = P:
    null passwords = no

Can anybody help please?

Thank you.

Axel.