right join 问题

select count(ID) as Count, bb.Code,
bb.Name
from aa
right join bb
on aa.code = bb.Code
group by aa.code

aa:
ID Code
1000 1
1001 1
1002 2
1003 2
1004 4

bb:
Code Name
1 a
2 b
3 c
4 d
5 e

应该出现以下结果：
Count Code Name
2 1 a
2 2 b
0 3 c
1 4 d
0 5 e

为什么只能出现一条count为0的数据，而最后一条0 5 e却出不来？
---------------------------------------------------------------

select isnull(count(ID),0) as Count, bb.Code,
bb.Name
from (select count(*) as R_count,code from aa group by code)AAA
right join bb
on aaa.code = bb.Code

---------------------------------------------------------------

up
---------------------------------------------------------------

select count(ID) as Count, bb.Code,
bb.Name
from bb
right join aa
on aa.code = bb.Code
group by bb.Code, bb.Name