在OnCreate()中添加如下代码为何不能实现插入菜单及菜单项操作
         CMenu m_Menu;
   m_Menu.CreatePopupMenu();
GetMenu()->InsertMenu(2,MF_BYPOSITION|MF_POPUP|MF_STRING,(UINT)m_Menu.hMenu,"月份");
GetMenu()->GetSubMenu(2)->InsertMenu(0,MF_BYPOSITION|MF_STRING,113,"一月份");//插入菜单项。
         GetMenu()->GetSubMenu(2)->InsertMenu(1,MF_BYPOSITION|MF_STRING,114,"二月份");