Why is the loan output blank in this query?

SELECT b.branch_id, loan.s LOAN

from branch b LEFT OUTER JOIN (SELECT a.open_branch_id, sum(a.avail_balance) s

FROM account a INNER JOIN product p

ON a.product_cd = p.product_cd

WHERE p.product_type_cd='LOAN'

GROUP BY a.open_branch_id) loan

ON b.branch_id = loan.open_branch_id

ORDER BY b.branch_id;