PayPal rest API 执行错误

我正在尝试在Wordpress主题中实现PayPal付款。我得到令牌，创建付款，将用户重定向到批准链接，从用户那里获得批准，但由于某种原因我无法执行付款" curl 响应为空。

这是代码（我仔细检查了执行 url 和令牌，它们是正确的）

if (isset($_GET['token']) && isset($_GET['PayerID']) ){
   $received_token     =   sanitize_text_field ( $_GET['token'] );
   $received_payerId   =   sanitize_text_field ( $_GET['PayerID'] );
   $execute_urls       =   get_option('paypal_processing');
   $payment_execute_url=   $execute_urls[$current_user->ID];
   $execute_urls[$current_user->ID]    =   '';
   update_option('paypal_processing',$execute_urls);
   $payment_execute = array(
    'payer_id' => $received_payerId
       );
   $json = json_encode($payment_execute);
   $json_resp = make_post_call($payment_execute_url, $json,$received_token);
   print_r($json_resp);
   echo "Payment Execute processed " . $json_resp['id'] ." with state '".    $json_resp['state']."'";
   }


 function make_post_call($url, $postdata,$token) {
    $curl = curl_init($url); 
    curl_setopt($curl, CURLOPT_POST, true);
    curl_setopt($curl, CURLOPT_SSL_VERIFYPEER, false);
    curl_setopt($curl, CURLOPT_HEADER, false);
    curl_setopt($curl, CURLOPT_RETURNTRANSFER, true);
    curl_setopt($curl, CURLOPT_HTTPHEADER, array(
            'Authorization: Bearer '.$token,
            'Accept: application/json',
            'Content-Type: application/json'
            ));
    curl_setopt($curl, CURLOPT_POSTFIELDS, $postdata); 
    #curl_setopt($curl, CURLOPT_VERBOSE, TRUE);
    $response = curl_exec( $curl );
    if (empty($response)) {
       // some kind of an error happened
           print 'curl error';
       curl_close($curl); // close cURL handler
     } else {
     $info = curl_getinfo($curl);
        //  echo "Time took: " . $info['total_time']*1000 . "ms'n";
    curl_close($curl); // close cURL handler
    if($info['http_code'] != 200 && $info['http_code'] != 201 ) {
        //echo "Received error: " . $info['http_code']. "'n";
        //echo "Raw response:".$response."'n";
        exit('paypal error');
     }
  }
     // Convert the result from JSON format to a PHP array 
    $jsonResponse = json_decode($response, TRUE);
    return $jsonResponse;
     }