void DisplayStaff()
    {
        ClsStaffCollection members = new ClsStaffCollection();

        LbStaffList.DataSource     = members.StaffList;
        LbStaffList.DataValueField = "StaffID";
        LbStaffList.DataTextField  = "ContactNumber";
        LbStaffList.DataBind();
    }
    protected void BtnApply_Click(object sender, EventArgs e)
    {
        ClsStaffCollection members = new ClsStaffCollection();

        members.ReportByContactNumber(TbContactNumberFilter.Text);
        LbStaffList.DataSource     = members.StaffList;
        LbStaffList.DataValueField = "StaffID";
        LbStaffList.DataTextField  = "ContactNumber";
        LbStaffList.DataBind();
    }