Problems with MVC - C #, EntityFramework

Getting a weird error after I tried to expand the MVC membership provider in my first MVC3 project.

Errors:

EntityType 'MembershipUser' has no key defined. Define the key for this EntityType.

EntitySet "MembershipUsers" is based on type "MembershipUser" that has no keys defined

I set asp.net standard membership, but added an extra table and model called UserDetails, where the foreign key is the UserId field in aspnet_Users.

Once the record has been inserted into the users table, I get the UserId and try to enter other data in the Useretails table, but this happens when these errors occur. Here is another relevant code. AccountController:

if (createStatus == MembershipCreateStatus.Success)
            {                    
                //Add other user details
                UserRepository _user = new UserRepository();
                UserDetails userDetails = new UserDetails();

                userDetails.EmployeeNumber = Request.Form["EmployeeNumber"];
                userDetails.Title = Request.Form["Title"];
                userDetails.FirstName = Request.Form["FirstName"];
                userDetails.Initials = Request.Form["Initials"];
                userDetails.Surname = Request.Form["Surname"];
                userDetails.Nino = Request.Form["Nino"];

                _user.AddUserDetails(userDetails, model.Email);
                return RedirectToAction("Welcome", "Home");
            }

UserRepository:

    public MembershipUser GetUserByEmail(string email)
    {
        MembershipUser user = Membership.GetUser(email);
        return user;
    }


    public void AddUserDetails(UserDetails userDetails, string email)
    {
        MembershipUser user = GetUserByEmail(email);
        Guid userGuid = (Guid)Membership.GetUser(email).ProviderUserKey;
        userDetails.UserID = userGuid; //Add UserID foreign key
        using (IntranetApplication db = new IntranetApplication())
        {
            db.UserDetails.Add(userDetails);
            db.SaveChanges();
        }
    }

The error starts the db.SaveChanges line.

MemberShip , , -, UserID ? , , , .

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