Cycling through folders

["Colin J. Raven" <me@xxxxxxxxxxxxxxx>]

I could sure use some help on this one.

Procmail delivers mail to various folders:
IN.mutt, IN.postfix and so on

After some reading, I discovered that you can
define the order that mailboxes are read in. So
I did this in .muttrc


mailboxes =+Maildir =+IN.mutt =+IN.postfix

Maildir being the main mailbox/directory/whatever because Courier IMAP 
is set up and mailbox format is "Maildir" so in my $HOME lives a 
subdirectory "Maildir"

BUT there appears to be some unexpected behavior.
I can't cycle through those mailboxes using the space bar (or any 
other way either apparently) unless I invoke "c" then "?" then 
navigate to the mailbox in question.

What am I doing wrong????
Advice and/or suggestions would be greatly appreciated. 


-Colin