How to extract an element with XPath?

Hello Guys!

I'm struggling with a TestCase in SoapUI 3.0.1 (Free).
The idea is to shoot a request, and from the response extract a value and put in to an other request.

The response I got from the first request looks like:

<soapenv:Envelope xmlns:soapenv="http://schemas.xmlsoap.org/soap/envelope/">
  <soapenv:Body>
      <_:save xmlns:_="http://www.xyz.se/wsdl" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://www.xyz.se/types">
        <_:a>
            <b/>
            <c>
              <epost>a@b.com</epost>
              <tekniskNyckel>54132737</tekniskNyckel>
            </c>
        </_:a>
      </_:save>
  </soapenv:Body>
</soapenv:Envelope>

Now I would like to extract the "tekniskNyckel" and put into my next request.

I have tried to extract it like:
declare namespace soap='http://schemas.xmlsoap.org/soap/envelope/';
declare namespace ns1='http://www.xyz.se/types';
declare namespace ns2='http://www.xyz.se/wsdl';
ns1:a/c/tekniskNyckel

But it does not manage to extract anything when I run it in SoapUI.

So if any one got any experiance about this please let me know.

Best regards
Fredrik