Pyzor installed and tested but not used by spamassassin

I have installed dcc and pyzor. DCC is working OK, but there is no evidence of PYZOR_CHECK in email headers.

I can confirm that pyzor is working from the following:

spamassassin -t -D pyzor < /usr/share/doc/spamassassin-3.3.1/sample-spam.txt

This gives the following summary:

Content analysis details: (1003.1 points, 4.0 required)

pts rule name description

-0.0 NO_RELAYS Informational: message was not relayed via SMTP
1000 GTUBE BODY: Generic Test for Unsolicited Bulk Email
1.1 DCC_CHECK Detected as bulk mail by DCC (dcc-servers.net)
2.0 PYZOR_CHECK Listed in Pyzor (http://pyzor.sf.net/)
0.0 DIGEST_MULTIPLE Message hits more than one network digest check
-0.0 NO_RECEIVED Informational: message has no Received headers

/etc/email/spamassassin/local.cf has the following additions:

pyzor_options --homedir /etc/mail/spamassassin dcc_path /usr/local/bin/dccproc use_pyzor 1 pyzor_path /usr/bin/pyzor

So it seems that pyzor works but spamassassin is ignoring it.

Any thoughts would be welcome!