title: Object reference not set to an instance of an object, Interface
body: <p>I know that this is one of the most encountered error but I am really struggling to get around it.
  i have a property on my Controller:
      <code>private readonly ISelectListFactory _selectFactory;</code>
  and a method that called to populate the viewbag
      <code>private void PopulateLists()
      {
              var continent = _selectFactory.GetItems();
       }</code> 
  and the interface</p>
  
  <pre><code>public interface ISelectListFactory
  {
      IEnumerable&lt;SelectListItem&gt; GetItems();
  
  }
  </code></pre>
  
  <p>and in the controller constructor I have the following:</p>
  
  <pre><code>public LocationController(ISelectListFactory selectFactory)
      {
          _selectFactory = selectFactory;
       }
  </code></pre>
  
  <p>but I am getting this error Object reference not set to an instance of an object and not sure how to overcome it.</p>
  
  <p>Regards</p>