I think this may not be specifically an OES problem, but as I'm trying
to run it on OES, I'm posting here.

I have created a user called shutdown whose intended use if for our
support staff to shutdown/reboot the OES server should it become
necessary. The user is configured to use as a shell a script that warns
them of what is about to happen, prompts for confirmation and then uses
sudo to run /sbin/halt.

Everthing works well up to the point where sudo is called whereupon it
prompts for a password and does not accept the shutdown user password.

My sudoers file has this:
Cmnd_Alias SHUTDOWN = /usr/bin/halt

shutdown ALL = SHUTDOWN

The script calls: