private void RemoveIndividualToActivity() { string errorMessage = String.Empty; if (assignedTree.SelectedNode != null) { if (activityDataSource.DataSource != null) { Individual peep = (Individual)assignedTree.SelectedNode.Tag; Activity act = (Activity)activityDataSource.DataSource; Controller.DeleteActivityIndividual(act, peep, out errorMessage); if (String.IsNullOrEmpty(errorMessage)) { act.IndividualList.Add(peep); refreshActivityTab(); } } } }