shared folders

[Scherff]

Hi,
i am stuck. Try to install shared folders - dovecot is running fine. ACL 
is working. But i can't get running the shared folders. Maybe someone 
can help.

This are the relevant conf. I think i have some mistake there - perhaps 
in location - changed try and error - stuck:

mail_home = /var/vmail/mailboxes/%d/%n
mail_location = maildir:~/mail:LAYOUT=fs

namespace {
   hidden = no
   ignore_on_failure = no
   list = children
   location = 
maildir:%%h/mail:INDEX=%h/mail/shared/%%u:CONTROL=%h/mail/shared/%%u
   prefix = shared/%%u/
   separator = /
   subscriptions = yes
   type = shared
}
namespace inbox {
   inbox = yes
   location =
   mailbox Archives {
     auto = subscribe
     special_use = \Archive
   }
   mailbox Drafts {
     auto = subscribe
     special_use = \Drafts
   }
   mailbox Notes {
     auto = subscribe
   }
   mailbox Sent {
     auto = subscribe
     special_use = \Sent
   }
   mailbox Spam {
     auto = subscribe
     special_use = \Junk
   }
   mailbox Trash {
     auto = subscribe
     special_use = \Trash
   }
   prefix =
}

plugin {
     # global acl - prevent expunche for some folder
      acl = vfile:/var/vmail/dovecot-acl
       acl_shared_dict = file:/var/vmail/db/shared-mailboxes.db
}

protocol imap {
   imap_idle_notify_interval = 15 mins
   mail_max_userip_connections = 30
   mail_plugins = " acl imap_acl"
}

protocol lmtp {
   mail_plugins = " acl"
}


Need some hint.

Thanks
Alfred