private void bt_Tim_Click(object sender, EventArgs e) { if (tb_giatu.Text != ""&&tb_giaden.Text!="") { lv_dsketqua.Items.Clear(); client = new ServiceReference1.Service1Client(); client.TimgiaCompleted += new EventHandler<ServiceReference1.TimgiaCompletedEventArgs>(TimgiaCallBack); client.TimgiaAsync(int.Parse(tb_giatu.Text),int.Parse(tb_giaden.Text)); } else { lv_dsketqua.Items.Clear(); client = new ServiceReference1.Service1Client(); client.LoadNHCFCompleted += new EventHandler<ServiceReference1.LoadNHCFCompletedEventArgs>(LoadNHCFCallBack); client.LoadNHCFAsync(); } }