Something is wrong with your steps and the service class hasn't been generated appropriately. Check your steps. I'm currently writing a series on how to integrate Dynamics AX through AIF with any external system.
Though I'm not finished with the series, I started with a traditional Document service and showed how to set one up. The first part of the series can be found here:
After I show all the SharePoint goodies, I'll go on and right a custom service next with MVC to create a mobile application.
But check the steps. Your error highly indicates that steps were missing.