I am developing a report to summarize some metrics (table "Report"). I have a problem with the total cost of material. Each products has costs, table "Products" shows that product 110101 has at 2013 a costs and at 2014 costs. In report I would sum the total cost of the products for a specific YearsInvoiceDate(example 2013), in reality, It sum both the costs at 2013 and 2014 for a specific "YearInvoicedate". YearInvoceData is a fiel into table "Invoice" The cost of material expression is Sum( [Invoiced Quantity]* [Matirial Cost] ).