Upgrading NT4.0 PDC to Win2000

Happy Holidays everybody.

I have two NT4 servers. I upgraded my PDC to 2000. Now I am facing Active Directory Installation Wizard. I tried to have my 2000 machine to joint the domain and I received this error: ?The domain ? mydomain.com? is not an Active Directory domain, or an Active Directory domain controller for the domain could not be contacted.?
I don?t want to lose my old network settings. Do you know the best way to finish this process? I need to know how to set the active directory after the upgrade.
Thank you for your time and help.
Regards