cognos-using If statement -Probelm with measure

I am creating a report in cognos Report Studio 10,using an if statement. For display of a Column chart. On X-Axis i am using an if statement as follows if (?Category?='Valve Material') then ([Relational Model].[Catalog Elements].[Valve Material]) else (if (?Category?='Valve Trim Characteristic') then ([Relational Model].[Catalog Elements].[Valve Trim Characteristic]) else ([Relational Model].[Catalog Elements].[Valve Rating])) and year in the series and in measure i have given Sales Quantity.

which resulted me a warning RQP-DEF-0578 A grand total will be returned for measure 'Component Sales Qty' in expression 'total([Presentation Layer].[Measure].[Component Sales Qty]

and its displaying the total value of sales quantity for all the inputs.

Can anyone please suggest what are changes to be done on the maesure to get the individual sales quantity.