I think there was some erroneous syntax...
The normal form for Datediff is
=DateDiff("increment here","[FirstDateFieldHere]","LastDateFieldHere")
Prod1_5: sum(iif((Datediff("d",[2]![CREAT_TMSTMP],date())>=1) And (Datediff("d",[production date],date())<= 5),1,0))
Hopefully that works but...