Problem in set analysis

[#1]

Hello

I have a problem

In my expression, I only want to count Besteknummer (=Tender number) where the

date in the field [Datum 7: Finale goedkeuring] is equal to the date in the field [Datum 1: Lancering Workflow]"

=Count(DISTINCT{<[Datum 7: Finale goedkeuring]={"=[Datum 1: Lancering Workflow]"}>}Besteknummer)

It doesn't work.

Can somebody help me ?

Thanks in adance

Marc