[imp] dbmail + not showing messages

[Marco Genise]

Hi list,

I've got a strange problem here with Horde/IMP. I was running CyrusIMAP
until a few weeks ago, and anything worked fine. But after I switched to
DBmail as IMAP server, I can't get any messages through Horde/IMP. I can
see the folder hierarchie of the logged in account, but selecting an
IMAP folder just shows me "There are no messages in this mailbox.". On
the other side IMP shows the count of new messages in INBOX in the
navigation. As mentioned, anything worked fine with CyrusIMAP as IMAP
server.
Authenticating through the IMAP server also works without any problems
with DBmail.
I also upgraded to latest versions, but there no change in behavior.
Current installed versions are:
Horde 3.0.3
IMP H3 4.0.2

My current config of IMP:
$servers['imap'] = array(
     'name' => 'MY IMAPHOST',
     'server' => 'MY IMAPSERVER',
     'hordeauth' => true,
     'protocol' => 'imap/notls',
     'port' => 143,
     'folders' => '',
     'namespace' => '',
     'maildomain' => 'MY MAILDOMAIN',
     'smtphost' => 'MY SMTPHOST',
     'smtpport' => 25,
     'realm' => '',
     'preferred' => '',
     'hierarchies' => array()
);

Anyone got a hint what's the problem here?

Thanks in advance for your help,

Marco Genise.