private void btnThem_Click(object sender, EventArgs e)
 {
     enable(true);
     deleteText();
     flag = true;
     lueMaNV.Properties.DataSource    = nvControl.getMaTenChucVuUCThemDangNhap();
     lueMaNV.Properties.DisplayMember = "MANV";
     lblMaDN.Text = frm.MaSoTuTang("ND", dnControl.getFullData());
 }