Set Analysis for not null values

[Jo94]

Hello everybody,

I often read posts from the community to help me solving problems, but this time I can't find anything regarding my trouble. So I need your help.

I need to keep in set analysis the values from my set which are not null...

What I'm trying to do is to count late orders (the ones "opened" and odler than 14 days) for each department of my company , but I only have to count the ones for whom the field "PDM.NUMERO" is null.

To achieve that I tought to subtract from the whole the  orders for whom the "PDM.NUMERO" equals 'something'  (the difference should be the null ones)😂

count(
{$<[ODL.STATO] = {'DA FARE', 'IN CORSO'}, [JOV.PREVENTIVO] = {"<=$(=today()-14)"}>
- <[ODL.STATO] = {'DA FARE', 'IN CORSO'}, [JOV.PREVENTIVO] = {"<=$(=today()-14)"}, [PDM.NUMERO] = {*}>}
[ODL.NUMERO]
)

And it works, but when representing it in the pie chart I lose the dimension of the department of competence (NOD.DESCRIZIONE_L1).

See the grey "-".

If I simply use 

count(

count(
{$<[ODL.STATO] = {'DA FARE', 'IN CORSO'}, [JOV.PREVENTIVO] = {"<=$(=today()-14)"}>}
[ODL.NUMERO]
)

I regularly obtain  

Wich includes the orders for whom the field "PDM.NUMERO" is not null.

Any help?

Thank you really much for support!