spamassassin bayes training

hi,

i am using postfix, dovecot, amavisd, spamassassin and clamav on centos 7

i have set up spamassassin to use bayes and i seem to be getting ham and 
spam flagged in a MySQL database.  my database is called sa_bayes and 
the table bayes_seen has records with flags s and h inside.

but nothing seems to be happening in terms of spam filtering.  i would 
expect anything that was suspected of being spam to be moved to the spam 
folder.

is there something i am missing in my amavisd config?

thanks in advance
Matthew