Failure to join existing domain

[Alex King]

Hi,

I pulled down samba from git (alpha 18), followed the HOWTO at 
http://wiki.samba.org/index.php/Samba4/HOWTO/Join_a_domain_as_a_DC

Trying to install a DC alongside an existing 2008R2 server with 
Exchange2007.

I installed a fresh Debian Stable base system in a VM.

I compiled, installed, set up DNS (pointed /etc/resolv.conf to the 
existing 2008 server) and Kerberos as in the howto.  kinit successfully 
gained a ticket, but samba-tool domain join failed with 
"ERROR(exception): uncaught exception - Failed to find a writeable DC 
for domain"

Reporting the failure as requested in the howto.  I have googled this 
error, without getting any advice that can get me further.

root at ad1:/usr/local/samba# /usr/local/samba/bin/samba-tool domain join 
servers.nzcuexchange.co.nz DC -Uadministrator 
--realm=servers.nzcuexchange.co.nz
Finding a writeable DC for domain 'servers.nzcuexchange.co.nz'
ERROR(exception): uncaught exception - Failed to find a writeable DC for 
domain 'servers.nzcuexchange.co.nz'
   File 
"/usr/local/samba/lib/python2.6/site-packages/samba/netcmd/__init__.py", 
line 167, in _run
     return self.run(*args, **kwargs)
   File 
"/usr/local/samba/lib/python2.6/site-packages/samba/netcmd/domain.py", 
line 151, in run
     machinepass=machinepass)
   File "/usr/local/samba/lib/python2.6/site-packages/samba/join.py", 
line 921, in join_DC
     machinepass)
   File "/usr/local/samba/lib/python2.6/site-packages/samba/join.py", 
line 66, in __init__
     ctx.server = ctx.find_dc(domain)
   File "/usr/local/samba/lib/python2.6/site-packages/samba/join.py", 
line 204, in find_dc
     raise Exception("Failed to find a writeable DC for domain '%s'" % 
domain)

I understand the exchange server schema may cause problems, but this 
seems like early in the process to luck out.

What could be causing this error?

Does anyone else have success joining alpha18 to a 2008 AD domain?  Has 
anyone else successfully got samba4 DCs running with the exchange schema?

My aim is to have all users in AD using a linux MTA, but a small subset 
of users will have email forwarded to exchange running on 2008.  If I 
can't have the exchange server running in the same domain as samba4, I 
might just keep them running in separate domains.

Thanks,
Alex