Web Forms :: Output Caching Doesn't Work With Rout Handler

I am trying to use output caching on my .net pages but it is not working when I use Route handlers to redirect request to actual page, but it works when I call the page directly.

also one more weird thing is that when I am debugging and using .net instance of IIS http://localhost:64293/test it is working, but when I deploy it and try to call the page it is not caching i.e. http://www.mydomain/test(but it works if I call the page directly)

I am using VS 2010, IIS 6.0, .net Framework 4

aspx page code is :

<%@ Page Language="C#" AutoEventWireup="true" MasterPageFile="~/Site.master" Title="Not Found" %>
<%@ OutputCache Duration="300" VaryByParam="*" Location ="Server" %>
<script runat="server">
protected void Page_Load(object sender, EventArgs e)
{
litPageTitle.Text = "<br/>Datetime: " + DateTime.UtcNow.ToString();
}
</script>

my global.asax.cs code is

public static void RegisterRoutes(RouteCollection routes)