我正在尝试使用 PayPal Sandbox 来测试自动信用卡处理，但遇到了问题。上周我的测试是“成功的”，因为当发生验证错误时，API 会阻塞，但至少我知道发生了一些事情。在清理了传递给 API 的代码后，我不再收到验证错误，只是内部服务错误，这种情况已经发生了四天。
这是日志文件显示的内容（此处删除了访问令牌，但它是在使用之前从 API 成功生成的）：
2013-07-01 16:47:00,845 [32944] 调试 PayPal.Manager.ConnectionManager [(null)] grant_type=client_credentials
2013-07-01 16:47:03,296 [32944] 调试 PayPal.Manager.ConnectionManager [(null)] 服务响应
2013-07-01 16:47:03,296 [32944] 调试 PayPal.Manager.ConnectionManager [(null)] {"scope":" https://api.paypal.com/v1/payments/ .* https:// api.paypal.com/v1/vault/credit-card https://api.paypal.com/v1/vault/credit-card/ .* openid","access_token":"[生成的访问令牌]", "token_type":"Bearer","app_id":"[app ID]","expires_in":28800}
2013-07-01 16:47:05,069 [32944] 调试 PayPal.PayPalResource [(null)] Content-Type:application/json
2013-07-01 16:47:05,069 [32944] 调试 PayPal.PayPalResource [(null)] 授权：Bearer [访问代码]
2013-07-01 16:47:05,069 [32944] 调试 PayPal.PayPalResource [(null)] 用户代理：PayPalSDK/rest-sdk-dotnet 0.7.1 ;lang=DOTNET;v=4.0.30319.18046;bit=64 ;os=Windows 8 6.2.9200.0;
2013-07-01 16:47:05,069 [32944] 调试 PayPal.PayPalResource [(null)] PayPal-Request-Id:303be909-4268-4909-b1cb-b51b6dc7ea54
2013-07-01 16:47:05,365 [32944] 调试 PayPal.Manager.ConnectionManager [(null)] {"intent":"sale","payer":{"payment_method":"credit_card","funding_instruments": [{"credit_card":{"number":"4111111111111111","type":"visa","expire_month":4,"expire_year":2017,"cvv2":"123","first_name":"First" ,"last_name":"Last","billing_address":{"line1":"123 Any St.","city":"City","country_code":"US","postal_code":"12345"," state":"OH"}}}]},"transactions":[{"amount":{"currency":"USD","total":"4.93","details":{"shipping":"3.55","subtotal":"1.30","tax":"0.08"}},"description":"Description"}]}
2013-07-01 16:47:35,657 [32944] 错误 PayPal.Manager.ConnectionManager [(null)] 错误响应：{"name":"INTERNAL_SERVICE_ERROR","information_link":" https://api.sandbox.paypal .com/docs/api/#INTERNAL_SERVICE_ERROR ","debug_id":"ce04de98d51f2"}
2013-07-01 16:47:35,657 [32944] INFO PayPal.Manager.ConnectionManager [(null)] 从服务器获取 InternalServerError 状态代码
2013-07-01 16:47:35,708 [32944] 错误 PayPal.Exception.PayPalException [(null)] HttpConnection 执行中的异常：流不可读。PayPal.Exception.PayPalException：HttpConnection Execute 中的异常：流不可读。---> System.ArgumentException：流不可读。在 System.IO.StreamReader..ctor（流流，编码编码，布尔检测编码FromByteOrderMarks，Int32 bufferSize，布尔leaveOpen）在 System.IO.StreamReader..ctor（流流）在 PayPal.HttpConnection.Execute（字符串 payLoad，HttpWebRequest httpRequest ) --- 内部异常堆栈跟踪结束 ---
对此有何建议？我真的不知道从这里去哪里。