create button ใน vb มีปัญหาเวลา click button ครับ ต้องคลิ๊กถึงสองครั้ง ครับ

 <asp:UpdatePanel ID="UpdatePanel1" runat="server"><ContentTemplate>
   <table border="0" cellpadding="0" cellspacing="0"><tr>  
       <td> <asp:Button ID="btnCat1" runat="server" CssClass="button" Text="category1" /> </td>
       <td><asp:Button ID="btnCat2" runat="server" CssClass="button" Text="category2" /></td>
       <td><asp:Button ID="btnCat3" runat="server" CssClass="button" Text="category3" /></td>                    
    </tr></table></ContentTemplate></asp:UpdatePanel>
   <table border="0" cellpadding="0" cellspacing="0"><tr>  
     <td class="txtbodybule" width="200" valign="top"> กลุ่มน้ำหนัก</td>
      <td height="70" align="left" valign="top">         
         <asp:Panel ID="Panel1" runat="server" ></asp:Panel>
      </td></tr></table>
 <asp:Label ID="lblCat" runat="server" Visible="false" Text="G1"></asp:Label>
 <asp:Label ID="lblWeight" runat="server" Visible="false" Text="10"></asp:Label>
 <asp:Label ID="lblProduct" runat="server" Visible="false" Text=""></asp:Label>                                              

Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
       createButton(lblCat.Text)
End Sub
Private Sub createButton(ByVal cat As String)
        Dim db As New Bcwebcheck.DBProxy_Bcweb_new
        Dim dr As SqlClient.SqlDataReader = Nothing
        Dim i As Integer
        db.AddParameter("@Cat", lblCat.Text.Trim)
        db.ExecCommand("sp_bcwebnew_Select_List_Weight", dr)
        While dr.Read
            Dim btn As Button = New Button()
            btn.ID = ("btnW" & dr.Item("ItemWeight").ToString())
            btn.Text = (dr.Item("ItemWeight").ToString())
            btn.Attributes.Add("runat", "server")
            btn.Attributes.Add("class", "button")
            AddHandler btn.Click, AddressOf btnW_Click  ' Add button click handler
            Panel1.Controls.Add(btn)
            i += 1
        End While
        db.CloseConnection()
    End Sub
Protected Sub btnCat1_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles btnCat1.Click
        lblCat.Text = "G1"
        'createButton(lblCat.Text)
        loadProduct(lblCat.Text, lblWeight.Text)
End Sub
Protected Sub btnCat2_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles btnCat2.Click
      ...
End Sub