Need help on query which show total sum of result incorrect

[zell dsf]

SELECT id_product,sum((COALESCE(received_qty, quantity)))
FROM (SELECT C.id_cart,C.received_qty,C.quantity , P.id_product,
PO.id_purchase_order, PO.status
FROM (SELECT * FROM cart_items WHERE id_cart IN (SELECT id_cart FROM purchase_orders)) AS C
LEFT JOIN products as P on p.id_product = c.id_product
LEFT JOIN purchase_orders AS PO ON C.id_cart = PO.id_cart ) AS A
GROUP By A.id_product

Process:

When user buy item and check out then there's cart and cart items table to store the transaction.
1 cart_id have many item which stored in cart items table.
After purchase succeed, then will generate a purchase order id and stored in purchase order table .
In purchase order table, id_cart and status will be stored.

From here, i am trying to calculate quantity based on id_product or id branch or etc from the purchase made. There is receiving and ordered quantity field, which in some cases quantity received field might be null, so i will take ordered quantity value.

The expected result should sum up the qty of product id from different cart and display them.