Kolab doesn't create my mailbox

[h3x0g3n]

Hi,

when creating a Kolab user account, Kolab doesn't create a mailbox. 
However I can successfully login into the Kolab administration interface 
and Horde. The login via Imap is also successful, but afterwards I get 
the error: "Mailbox does not exist".
I tried this[1] but it didn't help. The tcpdump command is disabled by 
my provider as I'm running a virtual server.
The only hint I found for my problem is a warning in syslog, which 
appears evry minute:
kolabd[29366]: SD Warning: Unauthorized connection from <my public IP>, 
closing connection

I would be very glad if someone could help or give me a hint

Stephan




[1]http://wiki.kolab.org/index.php/Kolab2_Server_Troubleshooting_-_LDAP#Does_the_replication_system_work.3F