[horde] courier-imap creating new folders won't work

[Ben Davis]

When creating a new imap folder, I get the error:
"The folder "test" was not created. This is what the server said: 
Invalid mailbox name"

Here's my servers.conf file:

$servers['imap'] = array(
    'name' => 'Mail Server',
    'server' => 'localhost',
    'hordeauth' => true,
    'protocol' => 'imap/notls',
    'port' => 143,
    'folders' => 'INBOX.',
    'maildomain' => 'example.com'.
    'smtphost' => 'localhost',
    'dotfiles' => true
);

If I type in  "INBOX.foldername"   It will create the folder.  If I just 
type in "foldername",  I get that error.  I would like to be able to 
just type in the folder name by itself.  All the mailing-list posts say 
to change the "folders" option to "INBOX.", but I've done this already.  
What's going on here?