title: PHP SoapClient returns null even thought there was a response
body: <p>Using the PHP SoapClient, I make a call to the WSDL at <a href="https://webservices-test.ede.de:9443/ibis/ws/WS_EXT_ELC?wsdl" rel="noreferrer">https://webservices-test.ede.de:9443/ibis/ws/WS_EXT_ELC?wsdl</a> and I get the following xml response (as indicated by <code>$soapclient-&gt;__last_response</code>)</p>
  
  <pre><code>&lt;?xml version='1.0' encoding='UTF-8'?&gt;&lt;soap:Envelope xmlns:ede="http://ede.de/webservices" xmlns:fn="http://www.w3.org/2005/xpath-functions" xmlns:soap="http://www.w3.org/2003/05/soap-envelope"&gt;&lt;soap:Body&gt;&lt;Response action="ELC" requestId="1" version="1.0"&gt;&lt;created&gt;2017-09-04T16:04:46.556+02:00&lt;/created&gt;&lt;StatusInformation&gt;OK&lt;/StatusInformation&gt;&lt;StatusCode&gt;0&lt;/StatusCode&gt;&lt;Payload&gt;&lt;SalesOrderSimulateConfirmation&gt;&lt;Items&gt;&lt;Item&gt;&lt;ID&gt;10&lt;/ID&gt;&lt;ProductID&gt;0003062700050&lt;/ProductID&gt;&lt;Price&gt;2.970&lt;/Price&gt;&lt;PositionPrice&gt;2.970&lt;/PositionPrice&gt;&lt;PriceUnit&gt;1&lt;/PriceUnit&gt;&lt;QuantityUnit&gt;ST&lt;/QuantityUnit&gt;&lt;QuantityAvailable&gt;1&lt;/QuantityAvailable&gt;&lt;QuantityProfile&gt;1&lt;/QuantityProfile&gt;&lt;Currency&gt;EUR&lt;/Currency&gt;&lt;Services /&gt;&lt;Schedules&gt;Geplante Liefertermine:  1 ST in KW 36.2017;&lt;/Schedules&gt;&lt;Remark /&gt;&lt;DangerMaterial /&gt;&lt;/Item&gt;&lt;/Items&gt;&lt;/SalesOrderSimulateConfirmation&gt;&lt;/Payload&gt;&lt;/Response&gt;&lt;/soap:Body&gt;&lt;/soap:Envelope&gt;
  </code></pre>
  
  <p>Nevertheless, the call to <code>$soapclient-&gt;simulateOrder()</code> returns <code>null</code>.  </p>
  
  <p>How do I get the PHP SoapClient to return an object instead of null?</p>
  
  <p>Note: The xml I use for the soap call is generated manually by an override to <code>SoapClient::__doRequest()</code>.  The code for the soap call looks like:</p>
  
  <pre><code>$soapClient = new SoapClient('https://webservices-test.ede.de:9443/ibis/ws/WS_EXT_ELC?wsdl', array(
      'cache_wsdl'   =&gt; WSDL_CACHE_NONE,
      'trace'        =&gt; true,
      'exceptions'   =&gt; true,
      'soap_version' =&gt; SOAP_1_2,
      'features'     =&gt; SOAP_SINGLE_ELEMENT_ARRAYS,
      'login' =&gt; '------', // cannot post here for security purposes
      'password' =&gt; '-----', // cannot post here for security purposes
      'stream_context' =&gt; (
          stream_context_create(array(
              'ssl' =&gt; array(
                  'verify_peer' =&gt; false,
                  'verify_peer_name' =&gt; false,
                  'allow_self_signed' =&gt; true
                )
           ))
  ));
  $result = $soapClient-&gt;simulateOrder();
  </code></pre>
  
  <p>No exceptions are thrown, but <code>$result</code> is <code>null</code></p>