Not Able to Add US Card in Android Pay App in India

I am implementing Android Pay in my app. For that i have followed all steps in android guide. Android Pay Guide Link

My Android Code is ready but i am unable to add card to Android Pay app to proceed further.

I have added US Card Details of CITI Bank but it is not accepting card.

Even i have added 2-3 US card details still i am stucked.

Can Anyone tell me how can i test that or any sandbox environment or any testing card details

Please help, Thanks in Advance.