[Dovecot] Invalid password encoding

[Kenny Dail]

ok so now I've got Dovecot 1.0rc15 started on the test server. however
it seems that the auth-workers don't like their job:
auth-worker(default): plain_md5_verify((null)): Invalid password encoding

What do I need to do to make their life easier?

Current dovecot.conf:
protocols = imap imaps pop3 pop3s
disable_plaintext_auth = no
login_greeting = amigo.net ready.
mail_location = maildir:%h/Maildir
namespace private {
   separator = .
   prefix = INBOX.
   inbox = yes
   hidden = no
}
mail_extra_groups = mail
mmap_disable = yes
lock_method = dotlock
first_valid_uid = 465
valid_chroot_dirs = /var/mail/virtual
maildir_copy_with_hardlinks = yes
protocol imap {
  mail_plugins = quota imap_quota trash
  login_greeting_capability = yes
  imap_client_workarounds = outlook-idle
}

protocol pop3 {
  pop3_uidl_format = %08Xu%08Xv
  mail_plugins = quota
  pop3_client_workarounds = outlook-no-nuls oe-ns-eoh
}
protocol lda {
  postmaster_address = postmaster at amigo.net
}
auth_default_realm = amigo.net
auth_username_translation = %@
auth_username_format = %Ln@%d
auth_worker_max_count = 60
auth default {
  mechanisms = plain login apop digest-md5 cram-md5
  passdb sql {
    args = /etc/dovecot/dovecot-sql.conf
  }
  userdb prefetch {
  }
  user = vmail
  count = 1
  socket listen {
    master {
      path = /var/run/dovecot/auth-master
      mode = 0660
      user = postfix
      group = mail
    }
    client {
      path = /var/run/dovecot/auth-client
      mode = 0660
    }
  }
}
plugin {
  quota = maildir
  trash = /etc/dovecot/dovecot-trash.conf
}

-- 
Kenny Dail <kend at amigo.net>