ASP.NET无法在锚点

Question

我的项目昨天工作了。但现在已经不行了。你怎么看为什么onserverclick of anchor无法正常工作

<a class="media-link" href="#" runat="server" onServerClick="sy15">
    <div class="overlay">
        <div class="descr"><div>
         <asp:Label ID="Label15" runat="server" Text="Label"></asp:Label>

         <asp:Label ID="Label155" runat="server" Text="Label"></asp:Label></div></div>
    </div>
    <asp:Panel ID="Panel15" runat="server" Width="654" Height="240">
    <asp:Image ID="Image15" runat="server" ImageUrl="img/urunler/indir.jpg" />

    </asp:Panel>
 </a>

C＃

public void sy15(Object sender, EventArgs e) 
{
     if (Session["kad"] != null)
        Response.Redirect("blogsingle.aspx?Image=" + Image15.ImageUrl + "&kad=" + Label155.Text + "");
     else
        Response.Redirect("register.aspx");
}