NIS problem

[Ben 'Bend Over' Dover]

The last couple of days I've bin trying to setup a box to authenticate
users from a NIS server. With the help of the Handbook pages I've done
that and it works.
But I can't seem to get the client to only accept users from a specific
normal group.

Out take from the 4.9Rel passwd man pages:
---
Using groups instead of netgroups for NIS overrides
FreeBSD offers the capability to do override matching based on user
groups rather than netgroups.  If, for example, an NIS entry is
specified as:
	   + at operator:::::::::
the system will first try to match users against a netgroup called
`operator'. If an `operator' netgroup doesn't exist, the system will
try to match users against the normal `operator' group instead.
---

I understod this so that if operator isn't a netgroup but normal group the
client will only add users from the NIS-server that belong to that group.
But I can't seem to get it to work!

Did I understand the text wrong or have someone else experienced this
problem?

I'd just like to know if this is possible to do or not!