how to count this

[maybelyn benitez]

hi this is my code and i cant get it right the total discount dont have the right values what will i do?

SELECT departmentcode as `DEPARTMENTCODE`,sum(discount) as `Total Discount`
from department D,scholarship S,program P,registration R,assessment A
where S.scholarshipid=R.scholarshipi
and R.programid=P.programid
and P.departmentid=D.departmentid
AND SY='2014-2015' AND SEM='1ST' AND isEnrolled!='NO'
group by 1
order by 1
this is my design
file:///C:/Users/User/Desktop/fd%20(5)/sql/OUTPUT/erd.bmp