First you will have to create 2 'Rank' pills (Rank Global & Rank Region) using the same calculation in both:
You will place Region, Stores, Rank Region, Rank Global on to the rows shelf.
Click on the drop down arrow for both Rank pills and convert them both to Discrete.
Click on the drop down arrow of your Rank Region pill again, then click on 'Compute using' and select 'Stores'.
See the image below: (I've used Category to depict Stores in my example)
Hope this helps