JoinDomainOrWorkgroup 1323 error unable to update the password

I am using the Win32_ComputerSystem WMI object to join machines to a domain with JoinDomainOrWorkgroup. Then I ran into an issue on XP/2003 where I would get this 1323 return code and it would fail. This looked to work find for server 2012 so I started digging.

From the MSDN documentation, error 1323 means  "error unable to update the password".  My first set of searches implied that the time was out of sync between the servers. Manual join worked fine and after syncing the time to the DC before the join, I had the same issue.

$wmi.JoinDomainOrWorkgroup("Domain","Password","UserName",$null,3) 

Then I found a comment here that said add the domain to the username.

$wmi.JoinDomainOrWorkgroup("Domain","Password","Domain\UserName",$null,3) 

And then it worked.