Unable to use country code for configure validation logic in Position page using VBS

Summary:

Navigation : My Client Groups » Workforce Stracture » Position page
Requirement: If Employee from country 'US or 'UK' then employee can select only 8 digit cost center otherwise error
For other country no valifation

Problem: I tried to use all coluntry code inside Field Values and Initial Field Values but no country code is working for this logic

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