ser-root element in SOAP response

Hello,
I’m pretty new to webMethods development, SOAP and web services, so please forgive me, if the subject of this thread is too trivial. I have a question regarding calling a web service implemented in IS.
I took a WSDL (document/literal/wrapped style) and created a SOAP implementation in IS using New=>Web Service Descriptor (WS-I compliant).
Then I called the service using soapUI. Looking at the response returned, I noticed a ser-root element at the topy of the soap body:

<SOAP-ENV:Envelope xmlns:SOAP-ENV="http://schemas.xmlsoap.org/soap/envelope/" xmlns:SOAP-ENC="http://schemas.xmlsoap.org/soap/encoding/" xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
   <SOAP-ENV:Header/>
   <SOAP-ENV:Body>
      <ser-root:myMethodResponse xmlns:ser-root="test.ws.tom.com">
         <tns:MyClass1 xmlns:tns="test.ws.tom.com">
...

Does anybody know what this entity means ? I would have expected the MyClass1 element to immediately follow the Body-element.
Meanwhile I have implemented a client and server from the same WSDL using AXIS2. The response from the AXIS-Service looks the same except that the ser-root element is missing.
Furthermore the AXIS client will not accept the response from the webMethods server because of that ser-root element.
Is the generation of this element realted to my WSDL ? Or is there a way to obmit that element from the response.

Thank you in advance for your advice.

There are several bugs/issues with the WSD auto generation and soap interpretation in 7.1. Take a look at this thread for the fixes - http://wmusers.com/forum/showthread.php?t=15055&page=2