SpamAssassin not checking spam?

[Damien McKenna]

I've got MS 4.22-5 and SpamAssassin 2.60 or something.  I've got it working
ok, but SpamAssassin doesn't seem to be including most of its usual checks in
the spam, it isn't catching 99% of the spam that it used to catch before.  It
will catch spam once-in-a-while, but usually only things like
FORGED_MUA_OUTLOOK.  Any ideas what I might have not configured correctly?
--
Damien McKenna  damien at mc-kenna.com  http://mc-kenna.com/