DAX - Monthly Totals Measure

Hi all,

I'm new to the forum and Dax and I'm hoping someone can help a measure. I have two tables of data "qry_data_opportunities" and "qry_period_matrix". Both are linked in my data model via a numeric "Period ID". I am looking to amend my measure so that I get the desired effect of showing "Period ID" where the count is 0, rather than only the "Period ID" where there was a value. The DAX that I have so far is;

TEST R1M :=
COUNTAX (
    FILTER (
        ALLSELECTED ( qry_data_opportunities ),
        qry_data_opportunities[Period ID] = MAX ( qry_data_opportunities[Period ID] )
    ),
    [Employee ID]
)

Can anyone help me modify this so I get the desired outcome? I have attached some screenshots which will hopefully articulate what I am trying to do.

Note: I'm doing all of my testing in PowerPivot before moving the model into PowerBI.

Thanks,

Andy

Data Model

Current ouctome of "TEST R1M" measureMockup of desired outcome of "TEST R1M" measure