protected void btnSearch_Click(object sender, EventArgs e)
        {
            string searchValue = txtSearch.Text;

            if (!searchValue.Equals(""))
            {
                List <StaffDTO> searchResult = new List <StaffDTO>();
                searchResult = dao.AdminSearchStaffByUsername(searchValue);
                Session.Add("AdminStaffSearch", searchResult);
                if (searchResult.Count() > 0)
                {
                    lblMessage.Text        = "";
                    gvStaffList.Visible    = true;
                    gvStaffList.DataSource = searchResult;
                    gvStaffList.DataBind();
                }
                else
                {
                    gvStaffList.DataSource = null;
                    gvStaffList.Visible    = false;
                    lblMessage.Text        = "No record found!";
                    lblMessage.ForeColor   = Color.Red;
                }
            }
        }