Adding Two Fields

I have two query fields that are created by a case statement. I created a Calculated Field in my report: Data Type Float, Calculation: Nothing, Perform Calculation On: query.Tuition + query.RoomBoard, Initial Value query.Tuition + query.RoomBoard, Reset Field When: Group Changes, Reset Group: ID

I get the following error when I run the report: query.Tuition + query.RoomBoard is not a valid ColdFusion expression.

What am I doing wrong?