sudo permission problem

i have lan setting all client fedora & ubuntu machine all user have to access NIS & NFS services via i want know how to give permission they are only halt machine & restart the /etc/init.d/nis service.
i gave this command sudoers file

%groupname localhost=/sbin/halt -p

%groupname localhost=/etc/init.d/nis restart

%groupname localhost=/etc/init.d/ypbind restart

but they are unable to restart & halt the services

showing a errors " user is not allowed to run sudo on machine-name. This incident will be reported.

"start-stop-daemon: warning: failed to kill 6580: Operation not permitted"