Crystal Report SUM Case when

Good Day Expert,

How can I apply this code in Crystal report? Bec im always got an error "DateDiff is out of range"

ISNULL(SUM(CASE when (DATEDIFF(dd,JDT1.RefDate,@Date) <=0)
then
case when syscred <> 0 then syscred * - 1
else sysdeb
end
end),0.00)

or

SELECT datediff("dd",{JDT1.RefDate},{?FromDate})
Case is >0: Sum({JDT1.BalDueDeb})-sum({JDT1.BalDueCred})
Default: 0