Que significa este error?

[Libras]

Código SQL:

SELECT CompanyName,t2.customerid,t2.max_fecha,orderid FROM Customers AS t1
LEFT JOIN 
(
SELECT customerid,MAX(ShippedDate) max_fecha,orderid
FROM orders
    GROUP BY customerid,orderid) AS t2 ON (t1.customerid=t2.customerid)