title: Test credit card numbers for use with PayPal sandbox
body: <p>I'm having trouble testing credit card payments with PayPal's sandbox. When viewing a buyer's sandbox account's profile from within developer.paypal.com, I can see the following credit card details:</p>
  
  <p><img src="https://imgur.com/30vKoxN.png" alt="account"></p>
  
  <p>Although, when using these details on the payment screen, I get the message "We're sorry, we can't complete this payment. Please try another card."</p>
  
  <p><img src="https://imgur.com/NPVqo3l.png" alt="error"></p>
  
  <p>I have read in other questions that you should be able to log into a sandbox account, go to add an additional credit card and it should generate some test numbers for you... However, when I do this, all of the fields are blank:</p>
  
  <p><img src="https://imgur.com/s8n4MDa.png" alt="add"></p>
  
  <p>I have also tried using some "valid" numbers (i.e. they pass the Luhn algorithm), but none of those worked for me either.</p>
  
  <p>I've also tried the numbers listed on this page: <a href="https://www.paypalobjects.com/en_US/vhelp/paypalmanager_help/credit_card_numbers.htm">https://www.paypalobjects.com/en_US/vhelp/paypalmanager_help/credit_card_numbers.htm</a> - They didn't work.</p>
  
  <p>I've tried both US and UK accounts. No luck.</p>
  
  <p>Any ideas?</p>