netdom join fails for Window 8 machines with access denied

Hi,

I am getting an "access denied" when joining Windows 8 machines remotely into a AD domain with the following command:

netdom join /domain:<fqdn>\<pdc><machine name> /ud:<dn>\Administrator /pd:<domain admin pw> /uo:<machine name>\Administrator
/po:<local admin pw> /pm:<machine pw> /ro /reb /verbose
Establishing a session with <machine>

Joining domain <fqdn>\<pdc>

Deleting the session with <machine name>

Access is denied.

The command failed to complete successfully.

I am running the command on the PDC. I am rather sure that the passwords are correct, furthermore I know that the error message is different if the local admin password is wrong. On the remote machine (to be joined), I do not see any failed login attempts in the log. Actually, I am running out of ideas, because we use the very same command for years and it worked until (including) Windows 7. Any ideas?

Thanks in advance,
Christoph