SQL语句中IN的有关问题

SQL语句中IN的问题
我的usersys表是这样的

submit_user表是

我的SQL语句是：
SELECT fullname, sum( jkd )
FROM submit_user
WHERE fullname
IN (

SELECT fullname
FROM usersys
WHERE Department = '影像制作部'
)
AND submit_date
BETWEEN '2012-08-09'
AND '2012-08-26'

但是得到的结果就不对，结果是

本来应该得到的是该部门全部人员jkd的和，但是就只出来一个人的，真是奇怪了，请各位帮我看看，哪里有问题？

------解决方案--------------------
SELECT fullname, sum( jkd )
FROM submit_user
WHERE fullname
IN (

SELECT fullname
FROM usersys
WHERE Department = '影像制作部'
)
AND submit_date
BETWEEN '2012-08-09'
AND '2012-08-26'
group by fullname