I believe you are having a data type mismatch issue. The sales value is a decimal and specifying "0" is an integer. You should be able to change it to Sum(IIf(Fields!Year.Value > 2008 And Fields!Year.Value < 2012 , Fields!Sales.Value, 0.00)) or else explicitly cast both values such as Sum(IIf(Fields!Year.Value > 2008 And Fields!Year.Value < 2012 , CDbl(Fields!Sales.Value), CDbl(0))).