CheckBox labelLayer

i need to show/hide a labelLayer in my c# application with a checkbox, but i have an issue that when label shows ( checkbox checked ) it does'nt hide whene the checkbox is unchecked,

        private void checkBox1_CheckedChanged(object sender, EventArgs e)
    {

        SharpMap.Layers.LabelLayer labelLayer = new SharpMap.Layers.LabelLayer("nom commune");
        PostGIS quart_pos = new PostGIS("Server=localhost;Port=5432;User=postgres;Password=aaaaaa;Database=MiniProjet", "quartierr", "geom", "libelle");
        VectorLayer countriesLayer = new VectorLayer("quartier", quart_pos);
        labelLayer.DataSource = countriesLayer.DataSource;
        labelLayer.LabelColumn = "NAME";
        labelLayer.Style.CollisionDetection = true;
        labelLayer.Style.CollisionBuffer = new SizeF(10, 10);
        labelLayer.MultipartGeometryBehaviour =
        SharpMap.Layers.LabelLayer.MultipartGeometryBehaviourEnum.Largest;
        labelLayer.Style.Font = new Font(FontFamily.GenericSansSerif, 8);

        if (checkBox1.Checked == true)
        {
            labelLayer.Style.ForeColor = Color.Black;
            carte.Layers.Add(labelLayer);
            Refresh();
        }
        else if(checkBox1.Checked == false)
        {
            carte.Layers.Remove(labelLayer);
            Refresh();
        }

    }