php SOAP请求发送空白元素

我对SOAP请求和SoapClient类相对缺乏经验。我试图调用web服务的一个函数，但当我看到正在发送的请求时，它显示了空白元素，我在其中提供了一组参数。所以我不确定我是否阅读wsdl不正确，或者这里有什么问题。

这是我的php:

$ns = 'http://www.WSAPI.AMS360.com/v3.0';
$response = $client->__soapCall('Login',array($loginData)); 
$clientLoginToken = $client->__getLastResponse();
//token coming back as header in soap response; strip out xml and only use the Ticket element
$clientLoginToken = strip_tags($clientLoginToken);
//need to send auth header back on subsequent requests
$soapHeader = new SoapHeader($ns,'WSAPISession',array('Ticket'=>$clientLoginToken));
//test to simply retrieve a customer record..
$customerData = array('CustomerGetByNumberRequest'=>
                     array('CustomerNumber'=>'00006195')
                );
//call CustomerGetByNumber function
$customer = $client->__soapCall('CustomerGetByNumber',
                                array($customerData),
                                null,
                                array($soapHeader),
                                $output_headers);

当我调用$client->__getLastRequest()时，这是传出的XML。正如您所看到的，CustomerGetByNumber元素是空的，尽管我正在为上面的__soapCall()提供参数。

<?xml version="1.0" encoding="utf-8"?>
<SOAP-ENV:Envelope xmlns:SOAP-ENV="http://schemas.xmlsoap.org/soap/envelope/" xmlns:ns1="http://www.WSAPI.AMS360.com/v3.0">
  <SOAP-ENV:Header>
    <ns1:WSAPISession>
      <ns1:Ticket>
           tcyOHI65U2H1yKsuvpahvoWzViAQy+tsWRElraBgKJewSQQJFi8cgS/9bjge5TlXlzH2XkxszR5u/i42dGjUnd+0JHOlQ1bJYbY5/cLgctvn4iTqoD9NPL67S0MvG5Uq
      </ns1:Ticket>
    </ns1:WSAPISession>
  </SOAP-ENV:Header>
  <SOAP-ENV:Body>
    <ns1:CustomerGetByNumber />
  </SOAP-ENV:Body>
</SOAP-ENV:Envelope>