[Samba] Unable to promote 2008 R2 server

[Kristofer Pettijohn]

I have successfully joined a 2008 R2 server to the domain, but am unable to promote it. 

Windows reports: 

The operation failed because: A domain controller could not be contacted for the domain <domain> that contained an account for this computer Make the computer a member of a workgroup then rejoin the domain before retrying the promotion. "Access is denied." 

This is in the Samba log: 

[2015/03/25 22:07:36.241735, 0] ../auth/ntlmssp/ntlmssp_sign.c:236(ntlmssp_check_packet) 
NTLMSSP NTLM2 packet check failed due to invalid signature! 


I have done this several times, changing the workgroup and re-joining, etc. I can't get this to go. 

I have forward and reverse DNS set up for both the existing DC and the one I am attempting to promote. 

I'm not sure where to go from here.