exim4 & spamassassin - no spam scanning

[Branden Faulls <bfaulls@omphe.com>]

After a recent upgrade to sarge, I decided to update exim to exim4.  This was 
fairly painless, until I tried to configure spamassassin.  

Following instructions at: http://koivi.com/exim4-config/

I added a transport to /etc/exim4/conf.d/transport/30_exim4-config_spamcheck
and a router to /etc/exim4/conf.d/router/850_exim4-config_spamcheck_router

Mail is still being delivered fine, but the SPAM headers are not being added 
to the received email and the /var/log/exim4/mainlog reports that mail is 
being collected and delivered immediately to the necessary Maildir folder.  

What am I missing?  How do I get Spamassassin to scan the mail and tag it so 
that I can filter it out  with .forward rules, as I had previously?  I 
upgraded in the hope I could get sa-learn working, but so far spamassassin is 
a non-starter.

Any help would be  appreciated.
-- 
Branden Faulls