title: The type or namespace name 'IDependencyResolver' could not be found
body: <p>Im currently new to C#, and Im following a book to learn C#. I have the following code:</p>
  
  <pre><code>using System;
  using System.Collections.Generic;
  using System.Linq;
  using System.Web;
  using EssentailToos.Models;
  using Ninject;
  
  namespace EssentailToos.Infrastructure
  {
      public class NinjectDependencyResolver : IDependencyResolver 
      {
  
          private IKernel kernel;
  
          public NinjectDependencyResolver(IKernel kernelParam)
          {
              kernel = kernelParam;
              AddBindings();
          }
  
          public object GetService(Type serviceType)
          {
              return kernel.TryGet(serviceType);
          }
  
          public IEnumerable&lt;object&gt; GetServices(Type serviceType)
          {
              return kernel.GetAll(serviceType);
          }
  
          private void AddBindings()
          {
              kernel.Bind&lt;IValueCalculator&gt;().To&lt;LinqValueCalculator&gt;();
  
          }
      }
  }
  </code></pre>
  
  <p>When I'm trying to run this, I get the error: <code>The type or namespace name 'IDependencyResolver' could not be found</code></p>
  
  <p>Im new to C#, so can anyone explain why I get this error message?</p>