测试Yar实例报错，求解决?报错

@雪候鸟 

Yar1.2.1+PHP Version 5.4.16

yar-server.php

<?php
class API {
    /**
     * the doc info will be generated automatically into service info page.
     * @params
     * @return
     */
    public function api($parameter, $option = "foo") {
        
    }

    protected function client_can_not_see() {
    }
}

$service = new Yar_Server(new API());
$service->handle();
?>

<?php
function callback($retval, $callinfo) {
     var_dump($retval);
}

$client = new Yar_Client('http://xxxx/test/yar-server.php');
$result = $client->api("parameter");
?>

Warning: [Debug Yar_Client 17:40:58.326291]: 1381661965: call api 'api' at (r)'http://gas.my/test/yar-server.php' with '1' parameters in /mnt/hgfs/www/xxxx/test/yar-client.php on line 7

Warning: [Debug Yar_Client 17:40:58.326393]: 1381661965: pack request by 'PHP', result len '87', content: 'a:3:{s:1:"i";i:1381661965;s:1:"m' in /mnt/hgfs/www/xxxx/test/yar-client.php on line 7

Fatal error: Uncaught exception 'Yar_Client_Protocol_Exception' with message 'malformed response header '<br /> <b>Warning</b>: Missing '' in /mnt/hgfs/www/xxxx/test/yar-client.php:7 Stack trace: #0 /mnt/hgfs/www/xxxx/test/yar-client.php(7): Yar_Client->__call('api', Array) #1 /mnt/hgfs/www/xxxx/test/yar-client.php(7): Yar_Client->api('parameter') #2 {main} thrown in /mnt/hgfs/www/xxxx/test/yar-client.php on line 7