Query aliases accessible in subquery

select user_id as uID, last_name, first_name, athlete, parent, coach, code,

       sum(points) as total,

       propoints as lifetime,

       (select count(*) / 7 from 

       		(select count(user_id), Date(created_at) AS DATE

       		  from user_propoints

       		  where user_id = uID

       		  group by date) as ac1)

        as activity

from user_propoints

left join users on users.id = user_id

left join countries on users.country = countries.id

group by user_id

order by total desc

Error in query (1054): Unknown column 'uID' in 'where clause'