Add measure Group By NIF values which are not "N/A"

Good afternoon,

I'm doing a power pivot with data of a datatable of drivers, columns are "company, department, driver id number, and document A".

What I'm trying to achieve is to create a measure grouping by idNumber (cause same driver can be in different departments), and count how many of them have anything on that "document A" column but "N/A" (accepted, rejected etc).

=COUNTX (
ADDCOLUMNS (
DISTINCT ( SummaryData_DataTable2[Driver ID Number]);
"CountPerDriver"; CALCULATE ( DISTINCTCOUNT ( SummaryData_DataTable2[Document A])
;FILTER(SummaryData_DataTable2;SummaryData_DataTable2[Document A] <> "N/A") )
);
[CountPerDriver]
)

It didn't work btw, I'm pretty noob, just tried things I saw but any of them are exactly what I'm looking for.

Thank you for your time!