容易的soap出错.

简单的soap出错...
一直报错：
锘?
Fatal error: Uncaught SoapFault exception: [Client] looks like we got no XML document in E:\xampp\htdocs\photowall\registeraction.php:22 Stack trace: #0 E:\xampp\htdocs\photowall\registeraction.php(22): SoapClient->__call('test', Array) #1 E:\xampp\htdocs\photowall\registeraction.php(22): SoapClient->test() #2 {main} thrown in E:\xampp\htdocs\photowall\registeraction.php on line 22

上面那个乱码有点诡异....因为它是在我没有输出任何东西的情况下出现的....
不知道是神马意思....
求问各位大神到底哪里出错了...


下面是代码：

一个类，在usrHelper.php中：

class usrHelper
{
	public function test()
	{
		return "this is a test";
	}
}
?>

require_once 'usrHelper.php';

$server = new SoapServer(null, 
		array('uri' => "usr_service"));
$server->setClass('usrHelper');
$server->handle();
?>

$client = new SoapClient(null, array(
      'location' => "http://127.0.0.1/photowall/server.php",
      'uri'      => "usr_service",
      'trace'    => 1 ));
//$client->addUsr($username,$password);
$ans = $client -> test();
echo $ans;