dovecot - Jun 2013 - Question on Director setup

Hello,

 I am following the wiki page to setup 2 IMAP servers Director. in each
server, I have created 2 sets of dovecot config file where

the first set is for imap proxy with director
the second set is for the imap backend

after this, I attempt to login IMAP through the imap-proxy on any machine
with several users. from the log, all users always go to the same IMAP
backend in Server 2, I don't see any user go to the IMAP backend in Server
1 at all. What could be the problem I have ?

- Joe