Sometimes, you get javax.xml.ws.WebServiceException: Unexpected response element ,,, error while running a bpel process from a client.
One way to get rid of this error is adding namespace attribute to the operation definition in the wsdl of the bpel process as follows:
<binding name="calculatorMtomWSDLPortTypeBinding" type="tns:calculatorMtomWSDLPortType">
<soap:binding style="rpc" transport="http://schemas.xmlsoap.org/soap/http"/>
<operation name="calculatorMtomWSDLOperation">
<soap:operation/>
<input name="input1">
<soap:body use="literal" namespace="http://j2ee.netbeans.org/wsdl/CalculatorMtom/calculatorMtomWSDL"/>
</input>
<output name="output1">
<soap:body use="literal" namespace="http://j2ee.netbeans.org/wsdl/CalculatorMtom/calculatorMtomWSDL"/>
</output>
</operation>
</binding>
in short, lack of the red stuff above, leads the mentioned problem..