无法获取在vb.net的webforms中单击了哪个动态添加的按钮

Protected Sub Page_Load(ByVal sender As Object, ByVal e As EventArgs)
    ' 动态创建按钮
    Dim btn1 As New Button()
    btn1.ID = "btn1"
    btn1.Text = "按钮1"
    AddHandler btn1.Click, AddressOf DynamicButton_Click
    PlaceHolder1.Controls.Add(btn1)

    Dim btn2 As New Button()
    btn2.ID = "btn2"
    btn2.Text = "按钮2"
    AddHandler btn2.Click, AddressOf DynamicButton_Click
    PlaceHolder1.Controls.Add(btn2)
End Sub

Protected Sub DynamicButton_Click(ByVal sender As Object, ByVal e As EventArgs)
    ' 获取触发事件的按钮的ID
    Dim clickedButton As Button = DirectCast(sender, Button)
    Dim clickedButtonID As String = clickedButton.ID

    ' 根据按钮ID执行相应的逻辑
    Select Case clickedButtonID
        Case "btn1"
            ' 处理按钮1的逻辑
            Exit Select
        Case "btn2"
            ' 处理按钮2的逻辑
            Exit Select
        Case Else
            ' 处理其他按钮的逻辑
            Exit Select
    End Select
End Sub