title: WPF Implementing INotifyPropertyChanged
body: <p>I have setup a property and implement INotifyPropertyChanged</p>
  
  <p>like so...</p>
  
  <pre><code>public event PropertyChangedEventHandler PropertyChanged;
  
  public FlowProcess LastSelectedFlowProcess
  {
      get { return _lastSelectedFlowProcess; }
      set
      {
          _lastSelectedFlowProcess = value;
          Notify("LastSelectedFlowProcess");
          UpdateFlows();
      }
  }
  
  private void Notify(string propName)
  {
      if (PropertyChanged != null)
          PropertyChanged(this, new PropertyChangedEventArgs(propName));
  }
  </code></pre>
  
  <p>I used this exact setup on other classes but for some reason  in the Notify method the PropertyChanged variable is coming back null.</p>
  
  <p>In other classes when this works the PropertyChanged event is not null and evaluates to a delegate? What am I missing here?</p>
  
  <p>I am calling the public accessor from inside the class would that make a difference?</p>