SlideShowExtender - when I click image rediret to product

Hi

I have one SlideShowExtender and when I click in one image I want to be redirected toproduct page. I tought That I can use the

ImageDescriptionLabelID="lblDescricao" or ImageTitleLabelID="lblTitulo" 

to write the link and redirect with 

Response.RedirectPermanent(lblDescricao.Text);

But that is not possible, the content of lblDescricao is empty.

Here is my aspx code:

<!-- script imagens --><asp:ScriptManager ID="ScriptManager1" runat="server"></asp:ScriptManager><asp:ImageButton ID="ImageButton4" OnClick="LinkProduto" ImageUrl="imagens_carousel/imagem1.jpg" Width="200px" Height="200px" CssClass="img-responsive img-thumbnail" runat="server"
               /><span>    <asp:Label ID="lblTitulo" runat="server" Font-Bold="True" Font-Overline="False" Font-Size="X-Large"  ForeColor="#FF3300" Visible="true"></asp:Label><asp:Label ID="lblDescricao" runat="server" Font-Bold="True" Font-Size="X-Large" ForeColor="#FF3300" Visible="true"></asp:Label>     </span><ajaxToolkit:SlideShowExtender ID="SlideShowExtender1"
           TargetControlID="ImageButton4" runat="server" AutoPlay="true"
           Loop="true" SlideShowServicePath="imagens.asmx"
           SlideShowServiceMethod="GetSlides" ImageDescriptionLabelID="lblDescricao" ImageTitleLabelID="lblTitulo"
           /><!-- fim script imagens --> 

And my web method

 [WebMethod]
    public AjaxControlToolkit.Slide[] GetSlides()
    {
        return new AjaxControlToolkit.Slide[] {
            new AjaxControlToolkit.Slide("imagens_carousel/imagem1.jpg", "Portes Grátis", "http://mariolopes.com"),
            new AjaxControlToolkit.Slide("imagens_carousel/imagem2.jpg", "Portes Grátis", "http://ccccc.com"),
            new AjaxControlToolkit.Slide("imagens_carousel/imagem3.jpg", "Portes Grátis", "etc etc"),
            new AjaxControlToolkit.Slide("imagens_carousel/imagem4.jpg", "Portes Grátis", "etc etc"),
            new AjaxControlToolkit.Slide("imagens_carousel/imagem5.jpg", "Portes Grátis", "links here")};
    }

any ideas?

Thank you