>Allow me to sum up.
>A Select with an agregate function can potentially return a null record.

Only if SELECT doesn't have GROUP BY but has WHERE clause that results in 0 records matching. It's covered in the help for SET ENGINEBEHAVIOR 90

>To deal with this feature one could
>

>if _Tally<1 or (_Tally=1 and isnull(evaluate(field(1)))
>   * actually nothing was found
>endif

I don't thibk there's a generic way to handle that besides SET ENGINEBEHAVIOR 80