I changed up the expression to test for zero at the beginning. The expression looks good and does not reflect any errors, but I still get the #Error in the field when the report is executed. Any ideas?

=iif(iif(Sum(Fields!AvgMonthDemand12PrimaryPart.Value, "PartNumber")=0

,Sum(Fields!TotalAvgMonthDemand12.Value, "PartNumber")+first(Fields!AvgMonthDemand12Prim.Value, "PartNumber")

,Sum(Fields!TotalAvgMonthDemand12.Value, "PartNumber"))=0,"Null",

(

iif(Sum(Fields!TotalInvPrimaryPart.Value, "PartNumber")=0

,Sum(Fields!TotalInv.Value, "PartNumber")+first(Fields!TotalInvPrim.Value, "PartNumber")

,Sum(Fields!TotalInv.Value, "PartNumber"))

+

iif(Sum(Fields!QTYonOrderPrimaryPart.Value, "PartNumber")=0

,Sum(Fields!TotalQTYonOrder.Value, "PartNumber")+first(Fields!QTYonOrderPrim.Value, "PartNumber")

,Sum(Fields!TotalQTYonOrder.Value, "PartNumber"))

+

iif(Sum(Fields!QTYonPMRPrimaryPart.Value, "PartNumber")=0

,Sum(Fields!TotalQTYonPMR.Value, "PartNumber")+first(Fields!QTYonPMRPrim.Value, "PartNumber")

,Sum(Fields!TotalQTYonPMR.Value, "PartNumber"))

)

/

iif(Sum(Fields!AvgMonthDemand12PrimaryPart.Value, "PartNumber")=0

,Sum(Fields!TotalAvgMonthDemand12.Value, "PartNumber")+first(Fields!AvgMonthDemand12Prim.Value, "PartNumber")

,Sum(Fields!TotalAvgMonthDemand12.Value, "PartNumber")))