private void Storyboard_Completed(object sender, EventArgs e)
{
Storyboard st = new Storyboard();
DoubleAnimation da = new DoubleAnimation()
{
From = 0,
To = 1,
Duration = TimeSpan.FromSeconds(2)
};
Storyboard.SetTargetProperty(da, new PropertyPath("Opacity"));
st.Children.Add(da);
st.Completed += St_Completed;
TL.BeginStoryboard(st);
}