[Dovecot] Question about "reply from worker without password scheme"

[Zoong PHAM]

I have dovecot-1.0-test64 installed on OpenBSD-3.6.
It works fine with local password.

Now I fail to get dovecot to use MySQL to query for user details.
Any help would be very appreciated.

Here are the details:

from /var/log/maillog:
   1) with "default_pass_scheme = PLAIN"
   
      Apr  3 07:20:22 www dovecot: Dovecot v1.0-test64 starting up
      Apr  3 07:20:23 www dovecot: auth(default): mysql: Connected to (null) (dovecot)
      Apr  3 07:20:23 www dovecot: auth-worker(default): mysql: Connected to (null) (dovecot)
      Apr  3 07:20:50 www dovecot: auth(default): client in: AUTH     1 PLAIN   service=IMAP    secured   lip=1.2.3.4 rip=5.6.7.8 resp=AGhhemVsQGhhemVscGhhbS5jb20AemhAMTlTQXZl
      Apr  3 07:20:50 www dovecot: auth-worker(default): sql(client at clientdomain.com,5.6.7.8): query: SELECT pass AS password FROM user WHERE user = 'client at clientdomain.com'
      Apr  3 07:20:50 www dovecot: auth(default): blocking(client at clientdomain.com,5.6.7.8): Received reply from worker without password scheme
      Apr  3 07:20:51 www dovecot: auth(default): client out: FAIL    1 user=client at clientdomain.com temp
      Apr  3 07:21:50 www dovecot: imap-login: Disconnected: Inactivity [5.6.7.8]
   
   2) with "default_pass_scheme = PLAIN-MD5"
      Apr  3 07:07:13 www dovecot: Dovecot v1.0-test64 starting up
      Apr  3 07:07:14 www dovecot: auth(default): mysql: Connected to (null) (dovecot)
      Apr  3 07:07:14 www dovecot: auth-worker(default): mysql: Connected to (null) (dovecot)
      Apr  3 07:07:47 www dovecot: auth(default): client in: AUTH     1 PLAIN   service=IMAP    se cured   lip=1.2.3.4 rip=5.6.7.8 resp=AGhhemVsQGhhemVscGhhbS5jb20AemhAMTlTQXZl
      Apr  3 07:07:47 www dovecot: auth-worker(default): sql(client at clientdomain.com,5.6.7.8): query: SELECT pass AS password FROM user WHERE user = 'client at clientdomain.com'
      Apr  3 07:07:48 www dovecot: auth(default): client out: FAIL    1 user=client at clientdomain.com


Command to start dovecot:
  /usr/local/dovecot/sbin/dovecot -c /usr/local/dovecot/etc/dovecot.conf

Part of /usr/local/dovecot/etc/dovecot.conf:
  ....
  disable_plaintext_auth = no
  ....

  # SQL database
  passdb sql {
    # Path for SQL configuration file, see doc/dovecot-sql.conf for
    # example
    args = /usr/local/dovecot/etc/dovecot-mysql.conf
  }
  ....

  # SQL database
  userdb sql {
    # Path for SQL configuration file, see doc/dovecot-sql.conf for
    # example
    args = /usr/local/dovecot/etc/dovecot-mysql.conf
  }
  ....

I also tried with "disable_plaintext_auth = yes" without any luck. 

/usr/local/dovecot-1.0-test64/etc/dovecot-mysql.conf:
   driver = mysql
   connect = host=/var/www/dovecot/mysql.sock dbname=dovecot user=dovecot
   password=secretpwDB
   default_pass_scheme = PLAIN
   password_query = SELECT pass AS password FROM user WHERE user = '%u'
   user_query = SELECT maildir AS mail, sysuid AS uid, sysgid AS gid FROM
   user WHERE user = '%n'

Manually query MySQL with username and passwd as specified
in /usr/local/dovecot-1.0-test64/etc/dovecot-mysql.conf:

   mysql> SELECT pass AS password FROM user WHERE user ='client at clientdomain.com';
   +-----------+
   | password  |
   +-----------+
   | secretpw  |
   +-----------+
   1 row in set (0.00 sec)
   
   mysql>

Thanks,
Zoong