[Evolution] filtering spam not working

[Raphael Clifford <raphael clifford net>]

evolution 1.2.2-1.ximian.1
spamassassin 2.41-1mdk
mdk 9.0

I am attempting to set up spam filtering using evolution and
spamassassin.  I have set up a filter with

"Pipe Message to Shell Command" set to /usr/bin/spamc -c 
and
"does not return" "0"

The actions are "move to folder" and "stop processing"

This set up fails to filter any mail.  However when I run /usr/bin/spamc
-c < msg.txt from the command line it seems to work fine (some messages
get a score of over 20 and the limit is clearly set to 5).

If I put "/usr/bin/spamc -c" in quotes it moves *all* incoming mail to
the spam folder.

ps auwx |grep spamd gives

root      1333  0.1  1.4 15692 1872 ?        S    11:43   0:02
/usr/bin/perl /usr/bin/spamd -d -c -a -H

What am I doing wrong??

Cheers,
Raphael

P.S. I even tried making a shell script that just contained 
/usr/bin/spamc -c
and it still failed to filter any mail.
P.P.S. I can see from top that spamc is running when the mail comes in.
There is just some problem with dealing with the exit code correctly I
would guess.
-- 
Raphael Clifford <raphael clifford net>