Php 贝宝退款交易API（NVP）问题

我正在尝试使用nvp的ReturnTransaction API作为

[METHOD]=>ReturnTransaction

仅通用响应字段作为对PayPal交易API操作（NVP）的响应返回 这是请求

Array
(
    [METHOD] => RefundTransaction
    [VERSION] => 54.0
    [USER] => abc***xyz.com
    [PWD] => asd******asd
    [SIGNATURE] => T535*****************************************qWE3
    [CURRENCYCODE] => AUD
    [TRANSACTIONID] => 1D4*******40913KKJ
)

这是我得到的答复

Array
(
    [TIMESTAMP] => 2014-11-11T11:40:57Z
    [CORRELATIONID] => 3dba******fce
    [ACK] => Success
    [VERSION] => 54.0
    [BUILD] => 13***072
)

问题是我得到的回应是成功，但只有公共领域存在。请帮忙

这就是我的函数的样子

private function nvpCall($transaction_id){

            $params['TRANSACTIONID']    = $transaction_id;
            $params['REFUNDTYPE']       = 'Full';

            $nvpArr = $params ;


            $nvpreq = array();

            $nvpreq['METHOD']       = urlencode($methodName);       
            $nvpreq['VERSION']      = urlencode('54.0');
            $nvpreq['USER']         = urlencode($this->pp_pro_username);
            $nvpreq['PWD']          = urlencode($this->pp_pro_password); 
            $nvpreq['SIGNATURE']    = urlencode($this->pp_pro_signature);
            $nvpreq['CURRENCYCODE'] = urlencode('AUD');
            $nvpreq = array_merge($nvpreq, $nvpArr);

            $strReq = '';

            foreach($nvpreq as $key => $val){

                if($strReq!='') {
                    $strReq.= '&';
                }
                $strReq.= $key.'='.urlencode($val);
            }

            $ch = curl_init();
            curl_setopt($ch, CURLOPT_URL, $this->api_endpoint);
            curl_setopt($ch, CURLOPT_VERBOSE, 1);
            curl_setopt($ch, CURLOPT_HEADER, 0);
            curl_setopt($ch, CURLOPT_SSL_VERIFYPEER, FALSE);
            curl_setopt($ch, CURLOPT_SSL_VERIFYHOST, FALSE);
            curl_setopt($ch, CURLOPT_RETURNTRANSFER,1);
            curl_setopt($ch, CURLOPT_POST, 1);
            curl_setopt($ch, CURLOPT_POSTFIELDS, $strReq);
            $response = curl_exec($ch);

            curl_close($ch);

            print_r($this->deformatNVP($response));     

        }

添加注释

---

现在我发现这不是代码的问题，而是在沙盒帐户中使用了另一个用户名、密码和签名！那么问题出在哪里呢？

你能粘贴来自PayPal的完整回复，其中包括相关id吗？不过它在沙盒帐户中使用了另一个用户名、密码和签名！那么问题出在哪里呢？