Count values that match the selected value in an different column

[Zak2]

Hi,

In this data 'Directorate From' is linked to a separate hierarchy table against a field called Directorate. Directorate is a field users can filter by in the app. I want to create a calculation so that when 'Dir A', for example, is selected, a count of matching values in the 'Directorate To'. However this should only be when 'Directorate From' doesn't equal 'Directorate To'. In the example below, the answer would be 2 (as highlighted) and not 3.

The calculation would go in a straight table.

I hope that makes sense.

Thank you.