Strange nis issue

I'm using NetBSD 3.1 on
a sun machine, sparc64, and trying
to get it to be a nis client. The server
is a freebsd 6.1-release server with everything
seeming to be set up correctly - in regards to the master.passwd.* maps
which I can view by using ypcat on the client, but
can't authenticate using passwords. doing:
su - tyler
as root will work, but doing:
su - test
password: blah
won't work, giving an incorrect password message.
Is there anything I can do about this, without using the push
thing in /var/yp/makefile to not create the secure maps, and putting the passwords in the unsecure passwd maps?
I'm not even sure if that would work. I've
checked /etc/nsswitch.conf, and it's set to
passwd: files nis
so it looks fine. Any suggestions?