lmtpd and sieve

[Ilya]

I have now setup my exim to use true lmtp, with deliver -l.
Normal email is delivered with no problem, fileinto sorts it ok.
However if email meets reject rule, than it is delivered to inbox and I see
this error in exim log:

2002-09-06 13:02:21 17nMUu-000GWE-00 == mail at krel.org T=local_delivery_cyrus
defer (-1): LMTP error after end of data: 421 4.3.0 lmtpd: couldn't exec

cyrus.conf:
  # at least one LMTP is required for delivery
  #lmtp         cmd="lmtpd -a" listen="lmtp" prefork=0
  lmtpunix      cmd="lmtpd" listen="/var/imap/socket/lmtp" prefork=0

srwxrwxrwx  1 cyrus  cyrus  0 Sep  6 13:01 lmtp
-rw-------  1 cyrus  cyrus  0 Sep  6 12:31 lmtp.lock
-rw-------  1 cyrus  cyrus  0 Sep  6 13:06 lmtpunix.lock

exim/configure:
local_delivery_cyrus:
        driver = lmtp
        command = "/usr/local/cyrus/bin/deliver -l"
        user = cyrus
        group = cyrus


also, do I understand correctly that lmtptest wont work on socket?