SimpleCursorTreeAdapter - “只应在光标有效时调用”

Question

我有一个从SimpleCursorTreeAdapter扩展的适配器，并附加到ExpandableListActivity。 每次设备更改方向时，SimpleCursorTreeAdapter都会抛出异常！ （仅当至少扩展了1个项目时） “java.lang.IllegalStateException：只应在游标有效时调用它” 我的OnCreate

protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.disciplines);
        dbHelper.open();
        dataCursor = dbHelper.getDisciplinesOneField();
        DisciplineAdapter adapter = new DisciplineAdapter(this, dataCursor,
                R.layout.discipline_row
                , new String[]{Discipline.NAME}
                , new int[]{R.id.discipline_row_name}
                , R.layout.lesson_child, new String[]{}, new int[]{});
        setListAdapter(adapter);
        registerForContextMenu(getExpandableListView());
    }

我的适配器：

private class DisciplineAdapter extends SimpleCursorTreeAdapter{
        public DisciplineAdapter(Context context, Cursor cursor,
                int groupLayout, String[] groupFrom, int[] groupTo,
                int childLayout, String[] childFrom, int[] childTo) {
            super(context, cursor, groupLayout, groupFrom, groupTo, childLayout, childFrom, childTo);
        }

        @Override
        protected void bindChildView(View view, Context context, Cursor cursor,
                boolean isLastChild) {
            super.bindChildView(view, context, cursor, isLastChild);
                    // Filling my views here
        }


        @Override
        protected Cursor getChildrenCursor(Cursor groupCursor) {
            long disciplineId = groupCursor.getInt(groupCursor.getColumnIndex("_id"));
            return dbHelper.getLessonsForDiscipline(disciplineId);
        }

    }

我做错了什么？缺什么？ 谢谢。