If you get the following error:
You have to be a member of Local Administrators group in order to run ADMT. : Access is denied. (0x80070005)
You are likely not running the command from an elevated command prompt. When you search for the error there are a lot of blogs talking about adding yourself to the domain admins group on both domains. This is true – but it is not your issue.
Re-run with elevated permissions.
(actually your first hint would probably have been that you got the error ” ‘admt’ is not recognized as an internal or external command, operable program or batch file.” and had to change to the c:\windows\admt directory)