Unread message count in shared folders

[T T]

Hello List,

I've set up a Cyrus IMAP server on Debian 6. I'm using the shared
folders. The problem is, a subscribed user cannot see the correct
unread messages count until she clicks the folder. So, given that a
user at our company may easily have half a dozen of shared folders,
important messages can stay unnoticed.

I've seen this behavior on Apple Mail and Thunderbird so far. So, it
is probably something about Cyrus settings?
What would make the unread messages count visible as in users Inbox?

Thanks,

Toomas