error message "The revision level is unknown" joining domain

[Guest]

I keep getting an error message when im attempting to join a workstation to a domain. The error message is "Joining domain, The revision level is unknown". The now workstation was a domain controller and was "dcpromo" back to a workstation. The workstation has SP4 while the domain controller had no service pack at the time. The domain controller has now been updated with SP4 and all computers rebooted but am still getting the error message. Have been searching on google but not getting much, any suggestions.