How to return Max date or Null (if there is a Null present)

Hi,

I have a query where I Group By an Equipment Number field and then, for each equipment Number, return the Max (latest) Forecast Delivery date.

The problem is where one or more entries for a given Equipment Number has a Null in the Forecast Delivery date field. In these cases I need to return Null.

So, I need something like: "Return Max if there is no Null, otherwise return Null" for my Forecast Delivery field.

I have no idea how to do this Access so any help would be greatly appreciated.

Thanks very much.

Dave