I am trying to implement the following INotifyPropertyChanged Extension:

[Automatically INotifyPropertyChanged](https://stackoverflow.com/questions/527602/automatically-inotifypropertychanged) (accepted answer)
<http://ingebrigtsen.info/2008/12/11/inotifypropertychanged-revisited/>

But I cant figure out why my PropertyChanged EventHandler stays null. :(

I did a very simple WPF Application to test it out, here is my XAML Code:

```
<StackPanel Orientation="Vertical">
    <TextBox Text="{Binding Path=SelTabAccount.Test, UpdateSourceTrigger=PropertyChanged}"></TextBox>
    <TextBox Text="{Binding Path=SelTabAccount.TestRelated, UpdateSourceTrigger=PropertyChanged}"></TextBox>
</StackPanel>

```

And my code behind:

```
public partial class MainWindow : Window, INotifyPropertyChanged
{
    public event PropertyChangedEventHandler PropertyChanged;

    private TabAccount _selTabAccount;

    public TabAccount SelTabAccount
    {
        get { return _selTabAccount; }
        set
        {
            _selTabAccount = value;
            PropertyChanged.Notify(() => this.SelTabAccount);
        }
    }

    public MainWindow()
    {
        InitializeComponent();

        SelTabAccount = new TabAccount()
        {
            Test = "qwer",
            TestRelated = ""
        };
    }
}

public partial class TabAccount : INotifyPropertyChanged
{
    private string _test;

    public string Test
    {
        get { return _test; }
        set
        {
            _test = value;
            PropertyChanged.Notify(() => this.Test);
            PropertyChanged.Notify(() => this.TestRelated);
        }
    }

    public event PropertyChangedEventHandler PropertyChanged;
}

public partial class TabAccount
{
    private string _testRelated;

    public string TestRelated
    {
        get
        {
            _testRelated = Test + "_Related";
            return _testRelated;
        }
        set
        {
            _testRelated = value;
            PropertyChanged.Notify(() => this.TestRelated);
        }
    }
}

```

In the code behind you will see one class (its partial for just random testing) with 2 properties that should notify a property change but nothing happens.

The NotificationExtension is a copy and paste from the links provided at top and is in a external cs file.

I have also tried to do the sample with the "normal" INotifyPropertyChanged implementation and this works as expected but I cant make it happen with this extension class.

Hope you can help me figure it out.
Thanks in advance.