I don't know what line because I don't see the whole code. You put closing tag after the SQL statement.
<cfquery name="Specify_The_Name_of_This_Query> <!--- Opening tag --->
<!--- SQL Statement --->
SELECT size, amount, id
FROM productsize
WHERE productid=#Session.ProductId#
ORDER BY id ASC
</cfquery> <!--- Closing tag --->
Make sure you specify the name of the query.