private void cboClass_SelectedIndexChanged_1(object sender, EventArgs e)
        {
            OnValueChanged("RefClassID", cboClass.GetValue());
            //string seatNo = cboSeatNo.Text;
            //SetSeatNo(seatNo);
            cboSeatNo.Text = "";

            //if (cboClass.GetValue() == "")
            //    cboSeatNo.Enabled = false;
            //else
            GetClassSeatNoList(cboClass.GetValue());

            try
            {
                KeyValuePair <string, string> kv = ((KeyValuePair <string, string>)cboClass.SelectedItem);
                DSResponse rsp = QueryClass.GetClass(kv.Key);

                // (string.IsNullOrEmpty(cboDept.Text))
                cboDept.WatermarkText = rsp.GetContent().GetText("Class/Department");
            }
            catch { }
        }