How let two Code List Date Type object interact

Hi,

I Create first Code List Data

Second Code List Data

and define two element in BO object and enhance screen

[Label("Continents")] element CodeContinents:Codelist1Code;

[Label("City")] element CodeCity:Codelist2Code;

and enhance screen (Customers -> Accounts)

When I choose Asia, I can only see Japan and China let me choose.

How do I let two code list data interact?

Use BCO? How to do that?

Any ideas or suggestions are very appreciated.

Thanks and Regards.

Daniel.