Why does MySql add zero to SUM(value)?

Question

MySQL

Actually, there is a request:

select u.*, s.name as status_name, s.color as status_color, max(l.lvl) as lvl, sum(pow.value) as pow
from do_user u
join do_levels l
JOIN do_user_status s ON u.status = s.id 
JOIN (select * from do_user_power where type = 1) pow ON u.id = pow.uid
WHERE u.id = 5 AND u.exp >= l.exp

pow outputs the value 3230 when a simple select with the same options outputs the number 323.
Why does mysql add 0 to the value and how can I get rid of it?

Answer 1

In general, the data on the hosting sites differed, yes.
Made an import from where it worked.

Answer 2

First, you wrote nonsense in the request.
Confused in a pack of identical aliases for tables and columns.
Secondly, the main problem you have is in JOIN.
The amount of data you have in a simple query and in a JOIN query is different, respectively, and different results.
Well, different behavior on hostings can also be due to different data.