Could you please attach packaged workbook (**.twbx)
I don't have this packaged together yet, mainly because I don't know how to do it! I'm assuming it would be a data blend?
Yes. If you are still doing data prep, it would be beneficial to confirm each sub-region has at least one value in each of your tables for the blend, and that they have the same spelling. You can fix all of this later, but its easier to do in the data prep stage.
Don't you have some data sets in excel?
Either tow files, two tabs in one file works.
Hopefully you can illustrate what you expect.