Find attached workbook that I have modified from the OnDemand Training "Creating a Bump Chart. Link is
I have added in the product and months that you had on the original workbook.
I put the worksheet with rank and product sales (as a double check) in a dashboard called //REPORT : Ranking of Products Sold by Month.
I struggled with the sorting and have got around it by creating parameters to select a Sales Reference Year and Month.
Created a calculated field "Sales Reference Point" and then used that as the sort criteria on the Product Name.
With best regards