[Exim] Help with vacation messages

Please ... help me with this ....

vacation_user:
driver = autoreply
subject = "${if def:h_Subject: {Re: $h_Subject:} {OUPS!!}}"
file = "${if exists {/exim/etc/vacation/msgs/${local_part}}}"
log = /exim/vacation/${local_part}/log
once = /exim/vacation/${local_part}/once
to = $reply_address
from = $local_part
user = mail

Director:
vacation:
  unseen
  no_expn
  no_verify
  condition = "${if or {{match {$h_precedence:} {(?i)junk|bulk|list}} \
                        {eq {$sender_address} {}}} {no} {yes}}"
  local_parts = lsearch;/maildata/exim/etc/vacation-users
  require_files = /exim/etc/vacation/msgs/$local_part
  transport = vacation_user
  driver = smartuser
  errors_to = aglait@???

and I get:
Expansion of "${if exists {/exim/etc/vacation/msgs/${local_part}/} }" failed
in vacation_user transport:
    missing or misplaced { or }

I count the { }´s and move its but I cant it to work ....
do you see the error ?? :-(