//grid view button event


        protected void DelegateConfirmBtn_Click(object sender, EventArgs e)
        {
            if (txtStartDate.Text == "" || txtEndDate.Text == "")
            {
                lblfrmDate.Text = "The Start Date and End Date can not be empty.";
            }
            else
            {
                lblfrmDate.Text = "";
                Staff  manager = (Staff)Session["LoginStaff"];
                String sfid    = (string)ViewState["delegateStaffID"];
                Staff  sf      = dac.getStaffBySfId(sfid);
                if (sf.Role_ID == "Staff")
                {
                    DateTime sd = TC.DateConvert(txtStartDate.Text);
                    DateTime ed = TC.DateConvert(txtEndDate.Text);
                    if (DateTime.Compare(sd, ed) > 0)
                    {
                        LBStatus.Text = "End date should be later than Start date";
                    }
                    else if (DateTime.Compare(sd, DateTime.Now) <= 0)
                    {
                        LBStatus.Text = "Start date should be later than today";
                    }
                    else
                    {
                        LBStatus.Text = "";
                        dac.createDelegateHistory(sfid, manager.Staff_ID, sd, ed);
                        Page.ClientScript.RegisterStartupScript(this.GetType(), "script", "<script>alert('Delegate success!')</script>");
                        PostBack();
                    }
                }
                else
                {
                    dac.updateDelegateHistory(sfid);
                    Page.ClientScript.RegisterStartupScript(this.GetType(), "script", "<script>alert('Undelegate success!')</script>");
                    PostBack();
                }
            }
        }