Troubleshooting Sandbox

[CoachChicHockey]

Hi,

I recently installed a wp plugin called simple membership on my site and now I want to test the payment with Sandbox.

I created the accounts as shown and used the credit card simulator for payment but each time I use it, it gives me this message: 

• We’re sorry, but we weren’t able to add this card. Please try a different card

Is anyone else having problems like this?  Is there something I am not doing right?

Thank you for your guidance,