In a environment we have a Domain controller that is Windows Server 2008 and the second DC is Windows Server 2003 R2. The actual function level of the AD was first Windows 2000 native. Now we want to add a additional DC with Windows Server 2008 R2. When I want to add him as a "additional Server in a existing domain" the message occurs "to install a domain controller into this AD Domain, you must first prepare the domain using "adprep/domainprep". After this error occurs we prepaired the domain to using Windows 2003 function level and raised the function level successfully to Windows 2003.
After that when we want to re-add the new DC the error still occurs.
Do you know what's the problem?
Thanks for your help.