Ben:

Whoops.  I am in error. The Private,(MASTER-LIST) configuration is working
properly. The problem was that I was using an e-mail address/password that
I had forgotten I'd quietly added to the MASTER-LIST for test purposes.  It
now gives the proper message (Sorry, you are not authorized to browse the
archives
of the LISTNAME list from the address you entered in the login screen) even
if I use an e-mail address that has a password registered on that LISTSERV.
Thanks for your help.

Mark