private void CommisionB_Click(object sender, RoutedEventArgs e) // { try { int num; if (!int.TryParse(CommisionTxtB.Text, out num)) { throw new ArgumentException("it must be a number"); } bl.Change_Commision(int.Parse(CommisionTxtB.Text)); } catch (Exception ex) { MessageBox.Show(ex.Message, "Manager Data", MessageBoxButton.OK, MessageBoxImage.Error); } }