Grouping UNION ALL

No matter how I try to group the record set generated by this query it just wont do it. Query works ok the problem is trying to Group by A

SELECT     [Stamp Country Code] + + [Stamp No] + + [Stock Type Code] AS A, 
           Quantity AS B, 
           Description AS C, 
           Price AS D

FROM       dbo.vwSalesInvoiceWHandling
UNION ALL
SELECT     [Stamp Country Code] + + [Stamp No] + + [Stock Type Code] AS A, 
           Quantity AS B, 
           Description AS C, 
           Price AS D

FROM       dbo.vwSalesInvoiceWOHandling