private void txtRangoAl_TextChanged(object sender, TextChangedEventArgs e) { try { if (Validacion.IsValidCodPapeleta(txtRangoAl.Text) || (txtRangoAl.Text) == "") { lblErrRango2.Content = "El Codigo de Papeleta no es Valido"; } else { lblErrRango2.Content = ""; if (this.txtRangoDel.Text != "" && this.txtRangoAl.Text != "") { this.lblCantidad.Content = (int.Parse(this.txtRangoAl.Text) - int.Parse(this.txtRangoDel.Text) + 1).ToString(); } } } catch (Exception ex) { this.lblCantidad.Content = "No numerico"; } }