使用REST API进行Docusign实时帐户身份验证无效

Question

I am new on Docusign. I have developed a application using REST API on PHP language. In demo account everything is working fine. But in live account does not working. Error is calling webservice and status is 0. I tried many way but can't solve. Please help me. My code for authentication is given below.

$integratorKey = 'xxxxxx';
    $email = 'xxxx';
    $password = 'xxxx';

    // construct the authentication header:
    $header = "<DocuSignCredentials><Username>" . $email . "</Username><Password>" . $password . "</Password><IntegratorKey>" . $integratorKey . "</IntegratorKey></DocuSignCredentials>";


    $url = "https://www.docusign.net/restapi/v2/login_information";
    $curl = curl_init($url);
    curl_setopt($curl, CURLOPT_HEADER, false);
    curl_setopt($curl, CURLOPT_RETURNTRANSFER, true);
    curl_setopt($curl, CURLOPT_HTTPHEADER, array("X-DocuSign-Authentication: $header"));

    $json_response = curl_exec($curl);
    $status = curl_getinfo($curl, CURLINFO_HTTP_CODE);
    //echo $status;
    if ( $status != 200 ) {
        echo "error calling webservice, status is:" . $status;
        exit(-1);
    }

    $response = json_decode($json_response, true);
    $accountId = $response["loginAccounts"][0]["accountId"];
    $baseUrl = $response["loginAccounts"][0]["baseUrl"];
    curl_close($curl);