如何在VBA Excel的子菜单下添加子菜单？

Private Sub UserForm_Initialize()
    Dim submenu As CommandBarPopup
    Dim subsubmenu As CommandBarPopup
    
    ' 创建主菜单
    Set submenu = Application.CommandBars("Worksheet Menu Bar").Controls.Add(Type:=msoControlPopup, Before:=6)
    submenu.Caption = "子菜单"
    
    ' 创建子菜单
    Set subsubmenu = submenu.Controls.Add(Type:=msoControlPopup)
    subsubmenu.Caption = "子菜单1"
    
    ' 添加子菜单项
    subsubmenu.Controls.Add Type:=msoControlButton, Before:=1
    subsubmenu.Controls(1).Caption = "子菜单项1"
    
    ' 创建另一个子菜单
    Set subsubmenu = submenu.Controls.Add(Type:=msoControlPopup)
    subsubmenu.Caption = "子菜单2"
    
    ' 添加子菜单项
    subsubmenu.Controls.Add Type:=msoControlButton, Before:=1
    subsubmenu.Controls(1).Caption = "子菜单项2"
End Sub