WPF: Slider doesnt raise MouseLeftButtonDown or MouseLeftButtonUp

<Slider Width="250" Height="25" Minimum="0" Maximum="1" MouseLeftButtonDown="slider_MouseLeftButtonDown" MouseLeftButtonUp="slider_MouseLeftButtonUp" />

private void slider_MouseLeftButtonDown(object sender, MouseButtonEventArgs e)
{
sliderMouseDown = true;
}

private void slider_MouseLeftButtonUp(object sender, MouseButtonEventArgs e)
{
sliderMouseDown = false;
}

this.AddHandler
(
    Slider.MouseLeftButtonDownEvent,
    new MouseButtonEventHandler(slider_MouseLeftButtonDown),
    true
);