procmail and mutt - not sorting?

[Dave W]

I've copied my ~/Mail, .muttrc, .fetchmailrc, and .procmailrc stuff from
my Libranet (debian-based) machine to this Ubuntu box, and it *almost*
works right.  For some reason, though, procmail doesn't sort... it all
goes into the inbox.  I'm trying to figure out if it's a user error on
my part (something I forgot to copy/edit/change/whatever) or some
peculiarity of Ubuntu that I haven't read about yet...

Any comments, Ubuntians?

Thanks --

david w