protected void ImgBtnSortDescNrOrdine_Click(object sender, ImageClickEventArgs e)
        {
            cblNrOrdine.Items.Clear();
            using (Entities db = new Entities())
            {
                var anni = (from o in db.ORDINI_PRELARE
                            select o.Numord).Distinct().ToList();

                cblNrOrdine.DataSource = anni.OrderByDescending(item => item);
                cblNrOrdine.DataBind();
               
            }
            
            var SelezioniNrOrdini = (HashSet<string>)Session["NrOrdini"];
            if(SelezioniNrOrdini.Count==0)
            {
                CkbxNrOrdine_CheckedChanged(this, null);
            }
            else
            {
                foreach (String valore in SelezioniNrOrdini)
                {
                    foreach (ListItem it in cblNrOrdine.Items)
                    {
                        if (it.Value == valore)
                        {
                            it.Selected = true;
                        }
                    }
                }
            }
              
            txtbxNrOrdine.Text = string.Empty;
            txtbxNrOrdine.Text = cblNrOrdine.SelectedValueList.ToString();
        }