[exim] Subject from .vacation.msg

Hello,

I've setup vacation but i can't get Subject from my .vacation.msg which
one contain a "Subject:" line followed the message

The autoreplied message have two subject line :

Subject: No Subject
Subject: Vacant

The first one is from exim process and the second from my .vacation.msg
file

Here is my config :

vacation_transport:
driver = autoreply
log = /usr/maildirs/${lookup{$local_part@
$domain}dbm{/usr/local/etc/exim/localusers.db}}/Maildir/.vacation.log
once = /usr/maildirs/${lookup{$local_part@
$domain}dbm{/usr/local/etc/exim/localusers.db}}/Maildir/.vacation.once
once_repeat = 7d
from = $local_part@$domain
to = "${if def:h_Errors-To: {$h_Errors-To:} {$sender_address}}"
file = /usr/maildirs/${lookup{$local_part@
$domain}dbm{/usr/local/etc/exim/localusers.db}}/Maildir/.vacation.msg
return_message
user = mailnull

I need to set the subject in my .vacation.msg, adding the following is
not what i want :
  subject = ${if def:h_subject: \
                {Auto: Re: ${rfc2047:${quote:${escape:${length_60:
$h_subject:}} }} }\
                {Auto: Vacant} \
            }

Could you help me ?

Didier