ADO.NET :: Retrieving Parent (POCO) Class In WCF

I have an interesting problem with a WCF Service I am creating. As background fodder my solultion uses MVC 3 RC2 as the web interface. I am developing the solution as an N-Tier application using the Entity Framework 4.0 with POCO Self Tracking Entities, repository and unit of work approach. I am using the STE's more as an advanced POCO since STE do not seem to play well as of yet in the real world as they were meant to and since they do seem to give me better interfacing with the DB through my layers still. Additionally, I am incorporating WCF into the solution as the backend for the models based on info I am reading and the fact that I will need to also access these services via a windows service app on the client computers.

So, I have a datastore which includes my edm and the repositories. The POCO STEs are generated in a separate layer in what I have called my Domain Models. Within my domain area I also have a Core app holding my utilities. I am currently incorporating an additional domain element as a WCF service using the RESTful template. This WCF will be servicing both my MVC controllers and a Windows Service app on the client computers.

Now, on to the problem: Within this solution I have an Entity Set of People (or Person?). Within that Entity set I have a chain of inherited entities as follows Person->User->StaffMember->Provider where Provider is the resultant child. Within my WCF I have a ProviderService, a StaffMemberService and a UserService. In each of these Services one of my OperationContracts is a Get(string id) amongst others. the Get(String id) contract is the one that is causing me problems. Within that Get(String id) contract I do the following for the User:

[Code]....

and for the Provider:

[Code]....

Now, what has gotten me completely confused is that the Provider one works like a charm. But if I use the UserService to call the User of the same Id (Since User is a base class for Provider, this should work) I get an error saying it was a bad service call. (The ProviderService, as stated works and returns all the correct data). When I debug it, the UserService Get(String id) function actually works as expected up to and through the return statement (ie the user variable actually contains all the proper data that I would expect on the call). It is only after the return that I get the web page giving me that error and points me to the help page for the service. (I am using the browser to view the results at this point only). </P><P>I am assuming it has something to do with serialization? But why is it displaying the derived class with all expected data, which yes does include the data not being displayed as a user data, I am calling the data using the same UserId. I am not expecting someone to inspect my code, but to be a traffic cop and point me in the direction I need to look.