I'm having trouble using nis netgroups to give sudo access.

OS: opensuse 12.3 64 bit

/etc/sudoers (just one line!!)....

Code:
+lx_engs       ALL = (root) PASSWD: ALL
Using
Code:
ypcat -k netgroup
I can see i am in the netgroup "lx_engs"

Yet when I run sudo I get...

[999] eomer jonb inputs/: sudo whoami
jonb's password:
jonb is not in the sudoers file. This incident will be reported.

And nis is working just fine, since I have successfully logged in.
/etc/passwd has at the end...
Code:
+::::::
at the botton, and /etc/nsswitch.conf has
Code:
passwd: compat
group:  compat
hosts:  files mdns_minimal [NOTFOUND=return] dns
networks:       files dns
services:       files nis
protocols:      files
rpc:    files
ethers: files
netmasks:       files
netgroup:       nis
publickey:      files
bootparams:     files
automount:      files nis
aliases:        files nis
shadow: compat
Any ideas as to what I can check?
And the above works just fine on centos 6.4 by the way.

Thanks in advance...