Not all folders showing on client after moving mail from kolab1 to kolab2 server

[Thomas Spuhler]

upgraded from kolab1 to kolab2 added all accounts using the web
interface and then moved the folders to the new location.
But the problem is that many of the subfolders don't show up in the mail
client, although they are on the server.
Also the login and opening of the folders take quite a long time.
Is there anything I need to do to get them showing (or recognized by cyrus?
Thomas