Hi, I can't figure out how to delete all subtask for task, and save it to database. I made this recursive function, which delete tasks from gantview, but allways throws exception when saving to database

 private void deleteTasksAndSubtasks(Task task)
        {
            if (task.Tasks.Count > 0)
            {
                for (int i = 0; i < task.Tasks.Count; i++)
                {
                    Task taskF = task.Tasks[i];

                    if (taskF.IsSummary == true)
                    {
                        for (int j = 0; j < taskF.Tasks.Count; j++)
                            this.deleteTasksAndSubtasks(taskF.Tasks[j]);

                        task.Tasks.Remove(taskF);
                    }
                    else
                    {
                        task.Tasks.Remove(taskF);
                    }
                }
            }
        }

And I call this function like this

 private void ultraGanttView1_TaskDeleting(object sender, TaskDeletingEventArgs e)
        {
            if (e.Task.IsSummary)
            {
                 deleteTasksAndSubtasks(e.Task);  saveTasks();
            }
        }

It can delete task and his subtask, but if subtask has its subtask, ie if it has more than 2 levels, it always throws exception. What could be the problem ?

And I have another question. When I right click on ganttview and in toolstrip click on "Add task below selected task" in database it saves changes, but it doesn't write Project Key for this subtask I created. So next time i reload project, task is not in list, but its in database. and Project Key value is null. I tried to set Project Key value in ultraGanttView1_TaskAdded function, like this

e.Task.Project = ultraCalendarInfo6.Projects[1];

but it doesn't write project key to database. Any solution for this ?