我创建了一个 PayPal 帐户，还创建了一个沙盒personal account以及business account.
从business account api我得到的凭据username:111abc.org中，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=');
当我在我的网站上登录贝宝帐户时，它显示添加信用卡号：，我从复制它 business account api credentials，但它显示这样的错误
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.
如何使用沙盒帐户测试我的贝宝？