问Paypal在沙盒帐户中不起作用

EN

我创建了一个PayPal帐户，还创建了一个沙箱personal account和business account。

从business account api credentials中，我得到了username:111abc.org、pwd :111、signature:A--hhshshhhhshsss。使用来自测试帐户的这些详细信息，我格式化了我的API请求

 define('API_USERNAME', '111abc.org');
 define('API_PASSWORD', '111');
 define('API_SIGNATURE', 'A--hhshshhhhshsss');
 define('API_ENDPOINT', 'https://api-3t.sandbox.paypal.com/nvp');
 define('PAYPAL_URL', 'https://www.sandbox.paypal.com/webscr&cmd=_express-checkout&token='); 

当我在我的网站登录到贝宝帐户时，它显示添加信用卡号码：，我从business account api credentials复制了它，但它显示如下错误

This credit card has been denied by the bank that issued your credit card. For details on why your card was denied, please contact your credit card issuer's customer service department. Or, you may want to try adding a different credit card.

如何使用沙箱测试我的paypal帐户？