Problem configuring sieve

[Jerry]

This is a fresh installation of dovecot on a FreeBSD 11 system. Trying
to run the following command produces this error:

sievec ./default.sieve
sievec(root): Debug: Loading modules from directory: /usr/local/lib/dovecot
sievec(root): Error: Couldn't load required plugin /usr/local/lib/dovecot/lib90_sieve_plugin.so: Can't load plugin sieve_plugin: Plugin is intended to be used only by binaries: lda lmtp (we're sievec)
sievec(root): Fatal: Internal error occurred. Refer to server log for more information.
*** Error code 89

This is my configuration:

# 2.2.22 (fe789d2): /usr/local/etc/dovecot/dovecot.conf
# Pigeonhole version 0.4.12 (c1c0a23)
# OS: FreeBSD 11.0-CURRENT amd64  zfs
auth_mechanisms = plain login
lda_mailbox_autocreate = yes
lda_mailbox_autosubscribe = yes
log_path = /var/log/dovecot.log
mail_debug = yes
mail_location = maildir:/var/mail/vmail/%d/gerard
mail_plugins = sieve
mail_save_crlf = yes
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 index ihave duplicate mime foreverypart extracttext
namespace inbox {
  inbox = yes
  location =
  mailbox Drafts {
    auto = subscribe
    special_use = \Drafts
  }
  mailbox Junk {
    auto = subscribe
    special_use = \Junk
  }
  mailbox Sent {
    auto = subscribe
    special_use = \Sent
  }
  mailbox "Sent Messages" {
    auto = subscribe
    special_use = \Sent
  }
  mailbox Trash {
    auto = subscribe
    special_use = \Trash
  }
  prefix =
}
passdb {
  args = scheme=CRYPT username_format=%u /usr/local/etc/dovecot/users/passwd
  driver = passwd-file
}
plugin {
  sieve_default = /usr/local/etc/dovecot/sieve/default.sieve
}
postmaster_address = postmaster at seibercom.net
service auth {
  unix_listener /var/spool/postfix/private/auth {
    group = postfix
    mode = 0666
    user = postfix
  }
  unix_listener auth-userdb {
    group = vmail
    mode = 0666
    user = vmail
  }
}
service dict {
  unix_listener dict {
    group = vmail
    mode = 0600
    user = vmail
  }
}
ssl_cert = </etc/ssl/demoCA/certs/dovecot.pem
ssl_key = </etc/ssl/demoCA/private/dovecot.pem
ssl_protocols = !SSLv2 !SSLv3
userdb {
  args = username_format=%u /usr/local/etc/dovecot/users/passwd
  driver = passwd-file
}
protocol lda {
  mail_plugins = sieve
}

There is nothing in the logs regarding this. Can anyone help me?

-- 
Jerry