=IIf([Result1]<4.1,0,
IIf([Result1]>6.5,([Result1]-[Pump Settings]![Target]),
IIf([Result1]>4<6.5,1,"")))
1) from that I would say that there should be 4 brackets not 3, but with 4 i get an error
2) the part ([Result1]-[Pump Settings]![Target]) should not be in brackets
the formula works if...