[fw-db] SOAP Call using Zend_Soap_Client

Hi everybody,

I'm trying to access a SOAP-Webservice using Zend_Soap_Client using this
code:

============
$client = new Zend_Soap_Client($wsdl);
$RequestHeader = array("Map24ID"=>"xxx");
$MapSearchFreeRequest = array("MaxNoOfAlternatives"=>3,

"SearchText"=>"Frankfurt, Uhlandstrasse");

// "searchFree" is the name of the Function
$client->searchFree(array($RequestHeader, $MapSearchFreeRequest)));
============

But this only throws the following error:
"Message: SOAPAgent.processSOAPRequest() Failure:
No Envelope-Node detected!"

Doing the same request with php's own SoapClient-Class works....
Maybe I use Zend's Class in the wrong way?

Thanks for any help in advance,
Daniel

P.S.: In the code-samples in the Zends Reference Guide,
there is also the SoapClient-Class used, NOT Zend_Soap_Client. Is this a
mistake?