sa-learn skips alot of msgs?

[Steve]

Hey, im new to spamassassin but im told this abnormal and to post here, when I 
run sa-learn --mbox --spam /home/freedom/kmail/spam I get:
Learned from 11 message(s) (40 message(s) examined).

why would 40 msgs be exculded? they are all spam msgs.

running:
GNU/Linux 2.4.22
Slack 9.1 i686
SpamAssassin version 2.63

thanks.

Steve.