[Samba] missing _msdcs

[banda bassotti]

Hi, I migrated windows 2008r2 on samba, everything or almost correctly
works except the dns. I realized that one entry is missing:

ldbsearch -H /var/lib/samba/private/sam.ldb -b
"DC=DomainDnsZones,DC=mydomain,DC=lan"  | grep DC=_msdcs

samba-tool dns serverinfo 192.168.0.1 -UAdministrator at mydomain.lan
Password for [Administrator at mydomain.lan]:
ERROR(runtime): uncaught exception - (9717, 'WERR_DNS_ERROR_DS_UNAVAILABLE')
  File "/usr/lib/python2.7/dist-packages/samba/netcmd/__init__.py", line
176, in _run
    return self.run(*args, **kwargs)
  File "/usr/lib/python2.7/dist-packages/samba/netcmd/dns.py", line 559, in
run
    None, 'ServerInfo')

how to fix?

thnx a lot