I have a database of students with their grades by year level. I use a table calculation to calculate the change in grade from one level to the next. How do I suppress the calculation in instances where the grades are not available? For example, student A first enrolled in Year 7 so there should not be any difference for that year. In this instance I would like to grade difference to appear as a blank rather than a zero as I need to re-export the results of the back to original database. The highlighted fields are incorrect and should be blank.