Calculation Query

Some of our customers order single items and some order in cases. We have the master item list set up as 1 for the Items per sales unit and some other number for the Quantity for Packaging uom. This latter # can vary for different items.

I defined a field called U_Case_order in the RDR1 table that will allow the order taker to enter a case quantity. I then set up a Query as follows:

SELECT T0.SalPackUn * T1.U_Case_order AS 'Quantity' FROM dbo.OITM T0 INNER JOIN dbo.RDR1 T1 ON T1.ItemCode = T0.ItemCode AND T1.ItemCode = T0.ItemCode.

Finally, I defined a formatted search for the Quantity field using this query to refresh when I leave the U_Cae_order column. The result is blank with no error message.

Can anyone help?