La URL de ASP.Net WebAPI no devuelve ningún dato

Estoy usando la base de datos Northwind para tratar de comprender WebAPI para Asp.Net.

Mis archivos de Modelo/Controlador/Global se muestran a continuación.

Cuando navego a localhost: xxxx/api/employees/5, va correctamente al controlador correcto:

' GET /api/employees/5
Public Function GetValue(ByVal ID As Integer) As Employee
    Dim emp As Employee = db.Employees.Find(ID)
    Return emp
End Function

...sin embargo emp devuelve Nulo/Nada.

La base de datos Northwind definitivamente tiene datos:

¿Alguien podría ver dónde me estoy equivocando, por favor?

Gracias, Mark

Modelos/Empleado.vb:

Imports System.Data.Entity

  Namespace MvcApplication21
  Public Class Employee
    Public Property EmployeeID() As Integer
    Public Property FirstName() As String
    Public Property LastName() As String
  End Class

  Public Class EmployeeDBContext
    Inherits DbContext
    Public Property Employees() As DbSet(Of Employee)
  End Class
End Namespace

Controladores/EmpleadosController.vb

Imports System.Web.Http
Imports MvcApplication21
Imports MvcApplication21.MvcApplication21

Public Class EmployeesController
Inherits ApiController

Private db As New EmployeeDBContext

' GET /api/employees
Public Function GetValues() As IEnumerable(Of String)
    Return New String() {"value1", "value2"}
End Function

' GET /api/employees/5
Public Function GetValue(ByVal EmployeeID As Integer) As Employee
    Dim employee As Employee = db.Employees.Find(EmployeeID)
    Return employee
End Function

Web.config:

<configuration>
  <connectionStrings>
    <add name="DefaultConnection" connectionString="Data Source=.\SQLEXPRESS;Initial Catalog=Northwind;Integrated Security=True" providerName="System.Data.SqlClient" />
  </connectionStrings>

Global.asax.vb

Imports System.Web.Http
Imports System.Web.Optimization

Public Class WebApiApplication
 Inherits System.Web.HttpApplication

 Shared Sub RegisterGlobalFilters(ByVal filters As GlobalFilterCollection)
    filters.Add(New HandleErrorAttribute())
 End Sub

 Shared Sub RegisterRoutes(ByVal routes As RouteCollection)
    routes.IgnoreRoute("{resource}.axd/{*pathInfo}")

    routes.MapHttpRoute( _
        name:="DefaultApi", _
        routeTemplate:="api/{controller}/{id}", _
        defaults:=New With {.id = RouteParameter.Optional} _
    )

    routes.MapRoute( _
        name:="Default", _
        url:="{controller}/{action}/{id}", _
        defaults:=New With {.controller = "Home", .action = "Index", .id = UrlParameter.Optional} _
    )
 End Sub