private void GroupByComboBox_SelectionChanged(object sender, SelectionChangedEventArgs e) { ImpBL bl = ImpBL.Instance; try { if (groupByComboBox.SelectedIndex == 0) { groupingDataGrid.Items.Clear(); groupingDataGrid.CanUserReorderColumns = false; groupingDataGrid.CanUserResizeColumns = false; groupingDataGrid.CanUserResizeRows = false; groupingDataGrid.CanUserSortColumns = false; var h = bl.groupHostsByNumberOfUnits(); foreach (var item in h) { groupingDataGrid.Items.Add(item); } } } catch (Exception ex) { MessageBox.Show(ex.Message); } }