The type [nameHere] registered for extension '[extensionHere]' could not be loaded

I've been learning and building JSONP Web services using WCF on fx3.5. You can read some of the trials I had at .NET ASMX - Returning Pure JSON? I finally got a sample running but now I am I am dove tailing it into my app.

• RivWorks.Web - the web site - located at http://dev.example.com
• RivWorks.Web.Service - the new JSONP services - located in http://dev.example.com/services/ - the web.config for the services reside here.

The web.config for the service:

  <system.serviceModel>
    <behaviors>
      <endpointBehaviors>
        <behavior name="JsonpServiceBehavior">
          <webHttp />
        </behavior>
      </endpointBehaviors>
    </behaviors>
    <services>
      <service name="RivWorks.Web.Service.CustomerService">
        <endpoint address=""
                  binding="customBinding"
                  bindingConfiguration="jsonpBinding"
                  behaviorConfiguration="JsonpServiceBehavior"
                  contract="RivWorks.Web.Service.ICustomerService" />
      </service>
      <service name="RivWorks.Web.Service.NegotiateService">
          <endpoint address=""
                  binding="customBinding"
                  bindingConfiguration="jsonpBinding"
                  behaviorConfiguration="JsonpServiceBehavior"
                  contract="RivWorks.Web.Service.INegotiateService" />
      </service>
    </services>
    <bindings>
      <customBinding>
        <binding name="jsonpBinding" >
          <jsonpMessageEncoding />
          <httpTransport manualAddressing="true"/>
        </binding>
      </customBinding>
    </bindings>    
    <extensions>
      <bindingElementExtensions>
        <add name="jsonpMessageEncoding"
             type="RivWorks.Web.Service.JSONP.JsonpBindingExtension
                 , RivWorks.Web.Service
                 , Version=1.0.0.0
                 , Culture=neutral
                 , PublicKeyToken=null"/>
      </bindingElementExtensions>
    </extensions>
  </system.serviceModel>

I am getting the following error and I've tried everything I can think of to fix it. Found a few typos (Sevice instead of Service) sprinkled throughout my code. I am using the sample code found at MSDN. Here is the error:

Configuration Error Description:** An error occurred during the processing of a configuration file required to service this request. Please review the specific error details below and modify your configuration file appropriately.

Parser Error Message: The type 'RivWorks.Web.Service.JSONP.JsonpBindingExtension
                , RivWorks.Web.Service
                , Version=1.0.0.0
                , Culture=neutral
                , PublicKeyToken=null' registered for extension 'jsonpMessageEncoding' could not be loaded.

Source Error:

Line 58:  <customBinding>
Line 59:      <binding name="jsonpBinding">
Line 60:          <jsonpMessageEncoding />
Line 61:          <httpTransport manualAddressing="true" />
Line 62:      <binding>

Source File: C:\RivWorks\dev\services\web.config    Line: 60

Version Information: Microsoft .NET Framework Version:2.0.50727.3603; ASP.NET Version:2.0.50727.3082

Does anyone have any ideas on what else I can check? There is a DLL called RivWorks.Web.Service.dll, it is being built and copied to the web site's bin directory. The services Web.config is being copied to the web site's Services directory. I don't have anything conflicting in the web site's web.config. I've checked all spelling problems.

Is the dll (RivWorks.Web.Service.dll) in the build output?

Next, try (for the "jsonpMessageEncoding" extension):

type="RivWorks.Web.Service.JSONP.JsonpBindingExtension, RivWorks.Web.Service, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null"

Note the different spacing both in terms of " , " and carriage returns.

After that, I would treble check the string. Write a console exe that references the dll you need (RivWorks.Web.Service), and output:

Console.WriteLine(
     typeof(RivWorks.Web.Service.JSONP.JsonpBindingExtension)
     .AssemblyQualifiedName);

That is the string you want in the xml, verbatim. Don't include any extra whitespace in this string.