OnViewAppearing XLabs Does it work?

Nothing seems to happen when I use OnViewDisappearing from my ViewModel.
I am using it like this

    public override void OnViewDisappearing ()
    {
        base.OnViewDisappearing ();
        System.Diagnostics.Debug.WriteLine ("Test");
    }

OnDisappearing works fine from the View

    protected override void OnDisappearing ()
    {
        base.OnDisappearing ();
        System.Diagnostics.Debug.WriteLine ("Test from view");
    }