Problem with dAvg syntac

[NNlogistics]

I want to be able to look at the average of a field when there is a entry in
another field and again when there is no entry in the other field.

So for no entry in "fldSupplierID
=DAvg("[TurnAroundTime]","qryQualityListRepairsShippedByDate","[fldSupplierID]is null") ' which seems to work?

and for an entry in "fldSupplierID". If the above worked the
=DAvg("[TurnAroundTime]","qryQualityListRepairsShippedByDate","[fldSupplierID]not isnull")
Doesnt

Any suggestions

 

[Klatuu]

It should be:
","[fldSupplierID] is not null")

IsNull is a VBA function. For SQL it is Is Not Null