Unmarshalling error

I am testing some API'S usig this SoapUI i got an error when testing one API .

can you please suggest how to solve that error and why the error is?

here,below is the error in xml format.

<soap:Envelope xmlns:soap="http://www.w3.org/2003/05/soap-envelope">
   <soap:Body>
      <soap:Fault>
         <soap:Code>
            <soap:Value>soap:Sender</soap:Value>
         </soap:Code>
         <soap:Reason>
            <soap:Text xml:lang="en">Unmarshalling Error:</soap:Text>
         </soap:Reason>
      </soap:Fault>
   </soap:Body>
</soap:Envelope>