title: WPF V4 - MVVM Light V4 (BL16 - Mix11) - RelayCommand - CanExecute doesn't fire
body: <p>I am trying to use the latest Preview version of MVVM-Light (V4 - BL16 - Mix11) in my WPF v4 app that was using MVVM-light V3 Sp1.</p>
  
  <p>In my ViewModel, I have the following property defined</p>
  
  <pre><code>    private WifiNetwork _selectedNetwork;
      public WifiNetwork SelectedNetwork 
      {
          get
          {
              return _selectedNetwork;
          }
          set
          {
              if (_selectedNetwork == value)
                  return;
  
              _selectedNetwork = value;
              RaisePropertyChanged("SelectedNetwork");
          }
      }
  </code></pre>
  
  <p>This property is binded to ListBox's SelectedItem in the View XAML.</p>
  
  <p>I have the following RelayCommand defined in my viewModel</p>
  
  <pre><code>    private RelayCommand _connectCommand;
      public RelayCommand ConnectCommand
      {
          get
          {
              if (_connectCommand == null)
              {
                  _connectCommand = new RelayCommand(
                      () =&gt; ConnectToSpecifiedNetwork(SelectedNetwork),
                      () =&gt; SelectedNetwork != null &amp;&amp; ! SelectedNetwork.IsConnected);
              }
  
              return _connectCommand;
          }
      }
  </code></pre>
  
  <p>This RelayCommand is binded to my "Connect" button.</p>
  
  <p>When the selected item is not already connected (IsConnected is false), then the connect button should enable.</p>
  
  <p>This worked perfect in MVVM-Light V3 Sp1. But when I use the MIX 11 preview version of MVVM-Light, this doesn't seem to work anymore.</p>
  
  <p>Any suggestions?</p>
  
  <p>I can upload my entire project somewhere if needed..</p>