I have a Stacked Chart and want to display the value with percentage. This is the dataset The Chart's label will become BLANK if using expression: String.valueOf((double)$F{cnt}/$F{total}) However if I change to String.valueOf((double)$F{cnt}/1000) It works, so how to field1 divide field2? It is so wried since this is very simple calculation and can be perform easily in SSRS or BIRT, but why so complicate in jasper report?