nbackup rights

I am trying to use nbackup to back up my nss file system. I can successfully run nbackup against a remote server as admin, but when I try to use another user it fails. I created a user with RWMF to the root directory for the server I want to back up, but when I try to run nbackup (with the same syntax that I use as admin), I get two errors

nbackup: unable to retrieve the target service name list
nbackup: connection denied

Since nbackup runs successfully as admin, I am thinking it is a rights issue somewhere but can't figure out where. Any ideas?

TIA,
-L