subject tag

Hello

I have a problem with the subject tag. I put this in the approriate part
of exim.conf

In the DATA ACL, put this:

warn message = X-New-Subject: *SPAM* $h_subject:
     spam = nobody


And this in system_filter.

In the system filter, put this:

if "${if def:header_X-New-Subject: {there}}" is there
then
   headers remove Subject
   headers add "Subject: $h_X-New-Subject:"
   headers remove X-New-Subject
endif

But the subject is not rewritten if Spamcore hits the threshold. It looks
like this then:

To: himbeere@blablabla
 Subject: VIAGRA
 Date: Sun, 11 Jul 2004 13:51:02 +0200
 User-Agent: KMail/1.6.2
 MIME-Version: 1.0
 Content-Disposition: inline
 Content-Type: text/plain;
  charset="iso-8859-15"
 Content-Transfer-Encoding: 7bit
 Message-Id: <200407111351.02384.himbeere@blablabla>
 Subject: ***SPAM*** VIAGRA
 X-Spam-Score: 6.9 (++++++)
 X-Spam-Report: Spam detection software, running on the system
"blablabla", has
        identified this incoming email as possible spam.  The original
message
        has been attached to this so you can view it (if it isn't spam) or
block
        similar future email.  If you have any questions, see
        root@localhost for details.
        Content preview:  click download [...]
        Content analysis details:   (6.9 points, 5.0 required)
        pts rule name              description
        ---- ----------------------
--------------------------------------------------
        2.8 SUBJ_VIAGRA            Subject includes "viagra"
        1.9 VIAGRA                 BODY: Plugs Viagra
        1.1 RCVD_IN_DSBL           RBL: Received via a relay in list.dsbl.org
        [<http://dsbl.org/listing?ip=212.202.36.60>]
        0.1 RCVD_IN_SORBS          RBL: SORBS: sender is listed in SORBS
        [212.202.36.60 listed in dnsbl.sorbs.net]
        1.0 DRUGS_ERECTILE         Refers to an erectile drug
 X-Spam-Flag: YES
 Status: R
 X-Status: N
 X-KMail-EncryptionState:
 X-KMail-SignatureState:
 X-KMail-MDN-Sent:

Someone has an idea what to try next?

regards
Thomas