Hide status bar on Android

Hello:

I try to hide the status bar on Android App (4.1), but I can not do it!

This is my start code:

[Activity (Label = "KioscApp", MainLauncher = true, Theme = "@android:style/Theme.Black.NoTitleBar.Fullscreen")] public class MainActivity : Activity {

protected override void OnCreate (Bundle bundle)
{
    base.OnCreate (bundle);
    this.Window.AddFlags(WindowManagerFlags.Fullscreen);
    SetContentView (Resource.Layout.Main);

    ...
}

}

It hides the App title bar, but not the back, home, clock, etc...

Thanks for your time!