AddHandler和AddressOf问题

我做了一个下拉框后，触发后动态生成了2个下拉框，代码如下Protected Sub ddlBelongs123_SelectedIndexChanged(ByVal sender As Object, ByVal e As System.EventArgs) Handles ddlBelongs123.SelectedIndexChanged
            Dim dpl As DropDownList = New DropDownList
            Dim dpl1 As DropDownList = New DropDownList
                dpl.ID = table3.Rows.Count
                dpl1.ID = table3.Rows.Count + 1
                upid1.Controls.Add(dpl)
                upid1.Controls.Add(dpl1)
 End Sub
我现在想触发dpl1下拉框的事件 要用到AddHandler： AddHandler dpl1.SelectedIndexChanged, AddressOf dpp


      Sub dpp(ByVal sender As System.Object, ByVal e As System.EventArgs)
            MsgBox("sdf")
        End Sub
请问我这个AddHandler dpl1.SelectedIndexChanged, AddressOf dpp
要加在那里啊，才能触发dpl1这个控件；