Web ASP.NET (VB) สอบถามเรื่องการรับ-ส่งค่าจาก Button ที่สร้างไว้ VB.NET ครับ

<asp:Panel ID="Panel1" runat="server">
                    </asp:Panel>
               <br />
                  <asp:Label ID="Label1" runat="server" Text=""></asp:Label>

 Private Sub loadUnit(ByVal productUnit As String)
        Dim unit() As String
        Dim i = 0
        Dim db2 As New Bcwebcheck.DBProxy_Bcweb_new
        Dim dr2 As SqlClient.SqlDataReader = Nothing
        unit = productUnit.Split("/", 1000, StringSplitOptions.RemoveEmptyEntries)
        For Each Str As String In unit
            db2.ClearParameters()
            db2.AddParameter("@Code", Str)
            db2.ExecCommand("sp_bcweb_Select_ProductUnit", dr2)
            While dr2.Read
                Dim btn As Button = New Button()
                ' btn.ID = "Button" + i.ToString()
                btn.ID = (dr2.Item("UnitCode").ToString())
                btn.Text = (dr2.Item("UnitName").ToString())
                btn.Attributes.Add("runat", "server")
                'btn.Attributes.Add("OnClick", "btn_Click")
                AddHandler btn.Click, AddressOf btn_Click
                Panel1.Controls.Add(btn)
                i += 1
            End While
            dr2.Close()
        Next
        db2.CloseConnection()
    End Sub
    Private Sub btn_Click(ByVal sender As Object, ByVal e As EventArgs)
        Label1.Text = String.Format("Button {0} was pressed.", CType(sender, Button).ID)
    End Sub