samba - May 2012 - Samba4 Can't join client to domain (Ubuntu 12.04 DC)

Hi
When I try to join a Linux client to the S4 domain I get:

net ads Join -UAdministrator
Enter Administrator's password:
Failed to join domain: failed to lookup DC info for domain 'POLOP.SITE' 
over rpc: Access denied

Administrator can kinit fine from the Linux client (Also Ubuntu 12.04)
Both DC and client can ping each other
Firewall is off at both ends
Apparmor is torndown at both ends

Client Samba(3) smb.conf (Works when connecting to an openSUSE Samba4 DC)

[global]
workgroup = CACTUS
realm = POLOP.SITE
security = ADS
kerberos method = system keytab

Any ideas? rpc: Access denied??

Cheers,
Steve