samba - Feb 1998 - NT PDC authentication failure

Is there anything special I should be aware of to make my NT PDC act  as
the password server? I've never been able to get this to work, though my
SDC and PDC's for other trusted domains seem to work fine. Could this be a
user rights issue on the server? Anyone else have this working okay (on NT
4.0?)

Thanks,

--Bruce