'message part refers a type not an element' when trying to create class proxy

Hello,

I'm having the message 'message part refers a type not an element' when I'm trying to generate a proxy from the wsdl from a schedule application. I couldn't see what's wrong in the aforementioned wsdl.

I made a sample from the original wsdl with only one operation causing this problem:

<?xml version="1.0" encoding="UTF-8"?>

<!-- Copyright INDEX EDUCATION  http://www.index-education.com/fr/ -->

<wsdl:definitions name="HpSvcWFR"

                  targetNamespace="http://www.indexeducation.com/frahtm/HpSvcW.html"

                  xmlns:hp="http://www.indexeducation.com/frahtm/HpSvcW.html"

                  xmlns:wsdl="http://schemas.xmlsoap.org/wsdl/"

                  xmlns:wsoap="http://schemas.xmlsoap.org/wsdl/soap12/"

                  xmlns:http="http://schemas.xmlsoap.org/wsdl/http/"

                  xmlns:xsd="http://www.w3.org/2001/XMLSchema">

<!-- ================= DÉFINITION DES TYPES ================= -->

  <wsdl:types>

  </wsdl:types>

  <wsdl:message name="ReponseNombreCours">

    <wsdl:part name="return"

               type="xsd:unsignedInt" />

  </wsdl:message>

  <wsdl:message name="RequeteNombreCours" />

  <wsdl:portType name="IHpSvcWCours">

    <wsdl:operation name="NombreCours">

      <wsdl:input message="hp:RequeteNombreCours" />

      <wsdl:output message="hp:ReponseNombreCours" />

    </wsdl:operation>

  </wsdl:portType>

  <wsdl:binding name="BindingCours"

                type="hp:IHpSvcWCours">

    <wsoap:binding style="rpc"

                   transport="http://schemas.xmlsoap.org/soap/http" />

    <wsdl:operation name="NombreCours">

      <wsoap:operation soapAction="urn:HpSvcW2015:IHpSvcWCours#NombreCours" />

      <wsdl:input>

        <wsoap:body namespace="http://www.indexeducation.com/frahtm/HpSvcW.html"

                    use="literal" />

      </wsdl:input>

      <wsdl:output>

        <wsoap:body namespace="http://www.indexeducation.com/frahtm/HpSvcW.html"

                    use="literal" />

      </wsdl:output>

    </wsdl:operation>

  </wsdl:binding>

  <wsdl:service name="HpSvcWDonnees">

    <wsdl:port name="PortCours"

               binding="hp:BindingCours">

      <wsoap:address location="http://polinycedev/hpsw/Cours" />

    </wsdl:port>

  </wsdl:service>

</wsdl:definitions>

Does anybody knows what could be the problem?

Thanks a lot.