private void btnDeleteTask_Click(object sender, RoutedEventArgs e) { if (lstManageTasks.SelectedIndex == -1) { MessageBox.Show("Please select a task to delete!", "Invalid Input", MessageBoxButton.OK, MessageBoxImage.Exclamation); return; } Task t = (Task)lstManageTasks.SelectedItem; TasksHelper client = new TasksHelper(); try { client.DeleteTask(user, event_.EventID, t.TaskID); int currIdx = cboRole.SelectedIndex; cboRole.SelectedIndex = -1; cboRole.SelectedIndex = currIdx; MessageBox.Show("Operation Succeeded"); } catch (Exception ex) { MessageBox.Show("An Error have occured: " + ex.Message, "Error", MessageBoxButton.OK, MessageBoxImage.Error); } finally { client.Close(); } LoadTasks(); }