Ubuntu 16.04 - net rpc join

Trying to join a machine to a domain.

This worked wellin 12.04

smb.conf
[global]
security = domain
netbios name = LD7vb2
realm = DOMAIN.COM
# originally we had "password server" but this is the recommended setting
wins server = ipbrick.DOMAIN.COM
workgroup = DOMAIN
# programatic UID calculation to make UIDs uniform accross machines
idmap config * : range = 2000-302000
idmap config * : base_rid = 0
idmap config * : backend = rid
winbind separator = +
winbind enum users = yes
winbind enum groups = yes
winbind use default domain = yes
#template homedir = /home/%D/%U
# WA folderview vs long paths
template homedir = /home/%U
template shell = /bin/bash
client use spnego = yes
domain master = no

Cant use it on Ubuntu 16.04

doing: net rpc join -U administrator
Result:
No realm has been specified! Do you really want to join an Active Directory server?
Enter administrator's password:
smb_signing_good: BAD SIG: seq 1
Failed to join domain: failed to lookup DC info for domin 'DOMAIN' over rpc: Access denied.

Can use: smbclinet -L ipbrick -U administrator and see infos about the server.

What can I do to join my machine to a domain with "net rpc join"?