Unable to select Field Parameters

Interesting, and good use of the parameters. 

Something you can consider is to have 3 columns, Country, State and City, but in the State column, for every Asian city, you just have "Asia" as the state.

Then you don't need parameters. You can have Country (Asia vs. N America) filter on the State/City slicer. You will have "Asia" as the top drop down, but if you leave it expanded it should do what you are hoping to do. 

Not as pretty but it would work.

Hi katari_123 ,

instead of assigning your field parameter "Dynamic Selection" to the "State, City" Slicer, you should simply assign State and City to the "State, City" Slicer. That worked for me:

Hope  that helps.