'n' doesn't work when using ediff -- an ediff beginners's quesstion

[Hendrik Boom <hendrik@topoi.pooq.com>]

This has got to be an utter beginners' question.  I've been using emacs 
for years, bot not ediff, and I must be doing something wrong with ediff.

ediff is started from monotone, my revision management system when its 
automatic merge mechanisms are not sufficient.  I gather this kind of 
thing is the principal use for ediff.

I'm running everything through a terminal emulator running ssh between 
two Debian Linux systems.  I get a text-mode XEmacs.

It has five panels -- and A and B for the files to be merged, a C for the 
merged file, an Ediff control panel (containing the line "Type ? for 
help", and the usual single-line command-entry line at the bottom (the 
place where ctl X ctl F would expect to be given a file name.

When the Ediff control panel is the current buffer, I type 'n' and get 
the message (in that bottom  line):

  No such coding system: emacs-internal

By the way, space gives me the same message.  'p' and 'P' both tell me 
"At beginning of the difference list", which is reasonable, and 'v' and 
'V' both scroll as expected, in opposite directions.

What could I possibly be doing wrong?

- hendrik