Fatal error: Uncaught SoapFault exception: 
[Client] Function ("getError") is not a valid method for this service in index.PHP:33
Stack trace: #0 index.PHP(33): SoapClient->__call('getError',Array) #1 index.PHP(33):
SoapClient->getError() #2 index.PHP(63): pay() #3 {main} thrown in /homeindex.PHP on line 33

这是我的代码：

<?PHP
    $client = new SoapClient('my soap server');
    $err = $client->getError();
?>

我应该如何在PHP Soap库中获得错误？