PayPal错误代码:580022 PayPal自适应并行付款

我正在尝试使用palypal自适应API进行并行支付。我正在发送这个数组。

Array
(
    [requestEnvelope.errorLanguage] => en_US
    [actionType] => PAY
    [cancelUrl] => http://www.consumersinchrist.org/
    [returnUrl] => http://www.consumersinchrist.org/
    [currencyCode] => USD
    [receiverList.receiver(0).email] => xxx@gxxil.com
    [receiverList.receiver(0).amount] => 3.00
    [receiverList.receiver(1).email] => sxxh.banerjee@xxe.com
    [receiverList.receiver(1).amount] => 56.00
)

我正在使用的代码..

$body_data = http_build_query($bodyparams, "", chr(38));

                    try
                    {
                    //create request and add headers
                    $params = array("http" => array(
                    "method" => "POST",
                    "content" => $body_data,
                    "header" => "X-PAYPAL-SECURITY-USERID: " . $API_UserName . "'r'n" .
                    "X-PAYPAL-SECURITY-SIGNATURE: " . $API_Signature . "'r'n" .
                    "X-PAYPAL-SECURITY-PASSWORD: " . $API_Password . "'r'n" .
                    "X-PAYPAL-APPLICATION-ID: " . $API_AppID . "'r'n" .
                    "X-PAYPAL-REQUEST-DATA-FORMAT: " . $API_RequestFormat . "'r'n" .
                    "X-PAYPAL-RESPONSE-DATA-FORMAT: " . $API_ResponseFormat . "'r'n"
                    ));

                    //create stream context
                    $ctx = stream_context_create($params);

                    //open the stream and send request
                    $fp = @fopen($url, "r", false, $ctx);
                    //get response
                    $response = stream_get_contents($fp);
                    //check to see if stream is open
                    if ($response === false) {
                    throw new Exception("php error message = " . "$php_errormsg");
                    }
                    //close the stream
                    fclose($fp);

但是我收到此错误：

ERROR Code: 580022 
ERROR Message: Invalid request parameter: receiverList cannot be null 

任何人请帮忙。