bayes score is higher in debug mode

[freightcar]

exim 4.50, spamassassin  3.0.3

I have spamd daemon running and when the message is checked automatically  
it gets BAYES_00 and when I check the same message in debug mode it gets  
BAYES_99 which means 6 pts less with default settings. all other test seem  
to get same result. where could be the problem?

tHanks