trouble with join and nested query

[abhiram p]

table temp has 2 fields login and cartId
table cart has cartId, quantity,size
table price_list has size,price

i want to get sum(quantity) for every size for a particular cartId.
since cart contains items of same size,size is redundant in cart.
and.. i dont know the cartId but i know the login whose cartid is needed.

i wrote the following query which did not work.

SELECT p.size,sum(c.quantity)
FROM price_list p, cart c
WHERE c.size=p.size AND c.cartId=(
SELECT t.cartId
FROM temp t
WHERE login='[e-mail]')
GROUP BY c.size;

please help me out.