Subject 'Invalid expression' error in GROUP BY when field based on a SQL statement is used in SELECT field list
This error: "Dynamic SQL Error SQL error code = -104 Invalid expression in the select list (not contained in either an aggregate function or the GROUP BY clause)" is returned by the following SQL:

            SELECT FIRST 1 S.Service FROM Service S
            WHERE (S.ServiceID = RL.ServiceID)
            ORDER BY RL.ReceiptLineID
            ) AS Service,
           SUM(Qty*Cost) Price  
        FROM ReceiptLine RL     
        GROUP BY ReceiptID, Service

Additional information:
The table ReceiptLine is a detail (as in master-detail) table that stores the line items relating to a purchase, with the fields ReceiptID and ServiceID being foreign keys. The Service table stores product/service names.

Using the ReceiptLine and Service tables, the SQL needs to provide the total of each receipt with only the first service name from the set of line items.

Is there an alternative way, using SQL only, to achieve the desired result?