NuSOAP サーバ側エラーの返し方

require_once('nusoap.php');

$server = new soap_server('my_webservice.wsdl');

function func1($param1, $param2, $param3){
    $fault = new soap_fault('server', '', 'faultstring', 'faultdetail');
    return $fault;
}

$server->service($HTTP_RAW_POST_DATA);