export purchase orders response

<s:Envelope xmlns:s="http://schemas.xmlsoap.org/soap/envelope/">
   <s:Body>
      <s:Fault>
         <faultcode xmlns:a="urn:microsoft-dynamics-schemas/error">a:Microsoft.Dynamics.Nav.Types.Exceptions.NavNCLEvaluateException</faultcode>
         <faultstring xml:lang="en-US">The value "" can't be evaluated into type Integer.</faultstring>
         <detail>
            <string xmlns="http://schemas.microsoft.com/2003/10/Serialization/">The value "" can't be evaluated into type Integer.</string>
         </detail>
      </s:Fault>
   </s:Body>
</s:Envelope>