diary in emacs 21.2

[Victor S. Miller]

I've been using the emacs calendar and diary for many years, without
much problem.  Recently, the linux systems where I work have been
upgraded so that the version of emacs used there is 21.2.  Now,
whenever I invoke calendar (I use Fancy diary entries), it craps out
after displaying the calendar with a message saying "Calendar buffer
is read only".  If I type 'd' (to get the diary display) I get the
same message.  Things work fine when I use emacs 20.7 (which are on
some other systems).  Strangely when I set debug-on-error to 't, it
does NOT give me an error traceback at all.  Does this sound like a
known bug in 21.2?

Victor Miller