dovecot - Dec 2012 - Problems trying to add dspam delivery to dovecot LDA to working Postfix/Dovecot server. No passdb.

Hello list,

I'm really hoping someone can point me in the right direction on this.

I set up a server using Postfix with LDAP lookups to Active Directory.
Postfix delivers to maildir.
Dovecot IMAP and POP are working correctly using PAM Kerberos to
authenticate via Active Directory.

I want to add spam filtering, so I'm trying to set up Postfix to use dspam
which is then supposed to use Dovecot LDA to deliver messages to the
mailbox instead of having Postfix deliver to the Maildir.

I can't get any deliveries to Dovecot LDA to get past passdb lookup.  When
I run

/usr/lib/dovecot/deliver -f bjarrett at garfield16.org -d
bjarrett at metcalfexcavation.com

I get:

Dec 19 20:57:55 mxserver2 dovecot: auth: Debug: master in: USER#0111#
011bjarrett at metcalfexcavation.com#011service=lda
Dec 19 20:57:55 mxserver2 dovecot: auth: Debug: password(
bjarrett at metcalfexcavation.com): passdb doesn't support credential
lookups
Dec 19 20:57:55 mxserver2 dovecot: auth: Error: static(
bjarrett at metcalfexcavation.com): passdb doesn't support lookups,
can't
verify user's existence
Dec 19 20:57:55 mxserver2 dovecot: auth: Debug: master out: FAIL#0111
Dec 19 20:57:55 mxserver2 dovecot: lda: Error: user
bjarrett at metcalfexcavation.com: Auth USER lookup failed
Dec 19 20:57:55 mxserver2 dovecot: lda: Fatal: Internal error occurred.
Refer to server log for more information.

so it doesn't even look like it's attempting to find the user. 
Here's my
doveconf -n:

# 2.0.19: /etc/dovecot/dovecot.conf
# OS: Linux 3.2.0-29-generic x86_64 Ubuntu 12.04.1 LTS ext4
auth_debug = yes
mail_gid = 1001
mail_location = maildir:/home/mailbox/%Lu/Maildir
mail_uid = 1001
managesieve_notify_capability = mailto
managesieve_sieve_capability = fileinto reject envelope encoded-character
vacation subaddress comparator-i;ascii-numeric relational regex imap4flags
copy include variables body enotify environment mailbox date ihave
passdb {
  args = /etc/dovecot/dovecot-ldap.conf.ext
  driver = ldap
}
passdb {
  driver = pam
}
plugin {
  sieve = ~/.dovecot.sieve
  sieve_dir = ~/sieve
}
protocols = imap pop3 sieve
service auth {
  unix_listener /var/spool/postfix/private/dovecot-auth {
    group = postfix
    mode = 0660
    user = postfix
  }
  unix_listener auth-userdb {
    group = mailbox
    mode = 0600
    user = mailbox
  }
}
ssl_cert = </etc/ssl/certs/dovecot.pem
ssl_cipher_list
ALL:!LOW:!SSLv2:ALL:!aNULL:!ADH:!eNULL:!EXP:RC4+RSA:+HIGH:+MEDIUM
ssl_key = </etc/ssl/private/dovecot.pem
userdb {
  args = uid=1001 gid=1001 home=/home/mailbox/%Lu/Maildir
allow_all_users=yes
  driver = static
}
protocol imap {
  imap_client_workarounds = delay-newmail
  mail_max_userip_connections = 20
}
protocol pop3 {
  mail_max_userip_connections = 20
  pop3_client_workarounds = outlook-no-nuls oe-ns-eoh
}
protocol lda {
  deliver_log_format = msgid=%m: %$
  mail_plugins = sieve
  postmaster_address = bjarrett at metcalfexcavation.com
  quota_full_tempfail = yes
  rejection_reason = Your message to <%t> was automatically rejected:%n%r
}

I have tried several configurations, but nothing seems to get me past the
"passdb doesn't support.." errors.