Windows 2003 DC on AD 2000 network

This is something I tried find out since 8 hours but no solution whatsoever, so I’d be very grateful if someone could help me out on this.

There is the situation: Win2k3 Std Server (primary) DC, Win2k Server fileserver.

I’m trying to join another Win2k3 server to the domain, but although I try to run /adprep forestprep and /adprep domain prep, the DCPROMO doesnt seem to recognize the adprep that is created on the pri-DC (Win2k3).

As the adprep is already done on the primary DC (win2k3) it doesnt allow to redo it.

Anyone have any clues where I have been going wrong ?