[Mimedefang] Changing subject

[Network Guy]

Hi All

Need to pointers please.

In filter_end I have changed action_change_header from:
("X-Spam-Score", "$hits ($score) $names);
to:
("Subject","$hits ($score) $Subject","1")
in an attempt to show the spam score on the subject line.  What happens is 
that a 'new' header shows up with what I want, NOT the Subject.  According 
to the HOWTO, this ...ahem... change should change the Subject -> what am 
I missing?

MD 2.39
SA 2.60
Mime-tools ( patched ) 5.41/02

Thanks

tod