private void TXT_L_NAME_KeyDown(object sender, KeyEventArgs e)
 {
     if (e.KeyCode == Keys.Enter)
     {
         TXT_TEL.Focus();
     }
 }
        private void BTN_SAVE_Click(object sender, EventArgs e)
        {
            if (TXT_F_NAME.Text.Length == 0)
            {
                TXT_F_NAME.Focus();
                MSGBOX mdg = new MSGBOX(MessageAlertHeder.Alert(), "PLEASE ENTER GUEST NAME!", MessageAlertImage.Alert());
                mdg.ShowDialog();
            }
            else if (TXT_TEL.Text.Length == 0)
            {
                TXT_TEL.Focus();
                MSGBOX mdg = new MSGBOX(MessageAlertHeder.Alert(), "PLEASE ENTER TELEPHONE NO!", MessageAlertImage.Alert());
                mdg.ShowDialog();
            }
            else if (TXT_ADULT.Text.Length == 0)
            {
                TXT_ADULT.Focus();
                MSGBOX mdg = new MSGBOX(MessageAlertHeder.Alert(), "PLEASE ENTER NO OF ADULTS!", MessageAlertImage.Alert());
                mdg.ShowDialog();
            }

            else if (CMB_RESERVE_BY.SelectedIndex == -1)
            {
                CMB_RESERVE_BY.Focus();
                MSGBOX mdg = new MSGBOX(MessageAlertHeder.Alert(), "PLEASE SELECT RESERVATION TYPE!", MessageAlertImage.Alert());
                mdg.ShowDialog();
            }
            else if (CMB_RESERVE_BY.SelectedIndex == 3 && CMB_AGENT.SelectedIndex == -1)
            {
                CMB_RESERVE_BY.Focus();
                MSGBOX mdg = new MSGBOX(MessageAlertHeder.Alert(), "PLEASE SELECT AGENT!", MessageAlertImage.Alert());
                mdg.ShowDialog();
            }
            else if (LST_SELECTED_ROOM.Items.Count == 0)
            {
                MSGBOX mdg = new MSGBOX(MessageAlertHeder.Alert(), "PLEASE SELECT ROOMS!", MessageAlertImage.Alert());
                mdg.ShowDialog();
            }
            else if (Convert.ToInt16(TXT_NO_OF_NIGHTS.Text) == 0)
            {
                MSGBOX mdg = new MSGBOX(MessageAlertHeder.Alert(), "PLEASE SELECT SPEND DATES!", MessageAlertImage.Alert());
                mdg.ShowDialog();
            }
            else if (CMB_TAX.SelectedIndex == -1)
            {
                MSGBOX mdg = new MSGBOX(MessageAlertHeder.Alert(), "PLEASE SELECT TAX TYPE!", MessageAlertImage.Alert());
                mdg.ShowDialog();
            }
            else if (CMB_AGENT.SelectedIndex > -1 && CMB_AGENT.SelectedIndex == -1)
            {
                MSGBOX mdg = new MSGBOX(MessageAlertHeder.Alert(), "PLEASE SELECT AGENT!", MessageAlertImage.Alert());
                mdg.ShowDialog();
            }

            else
            {
                BTN_SAVE.Enabled = false;
                SAVE_RESERVATION();
                BTN_NEW.Focus();
            }
        }