WSDL Newbie question

Hello all,

I am trying to understand WSDL at the moment and I have created a wsdl
file that I am running through Microsoft's wsdl validator service to see
how I am doing. The php script that is referenced in the wsdl file just
returns the sent string, its just a sample snippet.

The validator says the following to me:

Error: Element binding named hello_soap from namespace
http://web.njit.edu/~djv3/links/testing.wsdl is missing.This WSDL may be
naming the input message, but not using the same name within the binding
section. Try removing the names on the input and output elements within
the operation elements.

I'm thinking this is just a lack of understanding error but I am not
sure. If you have any resources that you use to aid in the creation of
wsdl files I would love to hear about them.

Below is the contents of the wsdl file I am validating.

Thanks,
Dan

<?xml version="1.0"?>
<definitions name="Test Response Service"
          targetNamespace="http://web.njit.edu/~djv3/links/testing.wsdl"
          xmlns:tns="http://web.njit.edu/~djv3/links/testing.wsdl"
          xmlns:xsd="http://www.w3.org/2000/10/XMLSchema"
          xmlns:soap="http://schemas.xmlsoap.org/wsdl/soap/"
          xmlns="http://schemas.xmlsoap.org/wsdl/">
<message name="incomingMessage">
        <part name="message" type="xsd:string"/>
</message>
<message name="outputMessage">
        <part name="retval" type="xsd:string"/>
</message>
<portType name="hello_soap">
        <operation name="hello_soap">
                <input message="tns:incomingMessage"/>
                <output message="tns:outputMessage"/>
        </operation>
</portType>
<binding type="tns:hello_soap" name="testingsoap">
        <soap:binding style="document"
transport="http://schemas.xmlsoap.org/soap/http"/>
        <operation>
                <soap:operation
soapAction="http://web.njit.edu/~djv3/links/testing.php"/>
                <input>
                        <soap:body use="literal"/>
                </input>
                <output>
                        <soap:body use="literal"/>
                </output>
        </operation>
</binding>
<service name="Test Response Service">
        <documentation>This is a WSDL file for my service</documentation>
        <port name="hellosoapport" binding="tns:hello_soap">
          <soap:address
location="http://web.njit.edu/~djv3/links/testing.php"/>
        </port>
</service>
</definitions>