I am doing routing in asp.net 4.0 but When the route is fired I’m getting a 404 error from IIS

public static string RegisterRoutes(string routes)
{
    string MainUrl = routes;
    string Url = null;
    string[] Urllast = null;
    string RouteUrl = null;
    try
    {
        if (routes.Contains("FinalRequestCompilation.aspx"))
        {
            RouteTable.Routes.Clear();
            Urllast = MainUrl.Split('/');
            Url = MainUrl.Split('/').Last();
            RouteUrl = Url.Split('.').First();
            RouteTable.Routes.MapPageRoute(RouteUrl, Urllast[6] + "/" + RouteUrl, "~/"+Urllast[6] + "/" + Url);
            return RouteUrl;
        }
        else
        {
            return routes;
        }
    }
    catch (Exception ex)
    {
        return null;
    }
}

protected void CMen_MenuItemClick(object sender, MenuEventArgs e)
{
    try
    {
        objMenuBal = new MenuBal();

        DataTable dt = new DataTable();
        if (e.Item.Value != "")
        {

            string code = e.Item.Value;
            string ServerIp = Request.Url.GetLeftPart(UriPartial.Authority) + "/";
            //DataSet ds = objMenuBal.GetHomeLink(code, "S", ref Err);
            DataSet ds = objMenuBal.GetHomeLink_Test(code, "S", ServerIp, ref Err);

            if (Err != "")
            {
                lblErrormsg.Text = Err;
                return;
            }
            else
            {
                string url = ds.Tables[0].Rows[0][0].ToString();
                // url = "~"+url.Substring(34, url.Length-34);

                objsession["SubModName"] = e.Item.Text;
                objsession["FormIDCode"] = e.Item.Value;
                objUserLogin.FormCode = e.Item.Value;
                string Form_Name = e.Item.Text;
                objUserLogin.FormName = Form_Name.Replace('>',' ');
                Session["Event"] = "";
                objsession["PageName"] = url;
                Session["objUserLogin"] = objUserLogin;
                DataSet dtSystemActivation = objMenuBal.GetSystemActivation(code, "A", ref Err);
                if (Err != "")
                {
                    lblErrormsg.Text = Err;
                    return;
                }
                else
                {
                    if (dtSystemActivation.Tables[0].Rows[0][0].ToString() == "")
                    {
                       insertInSession_Log(); //  /*keep session log of each link visit.*/

                        if(ddlParentMenu.SelectedItem.Text=="Master")
                        {
                            if (objsession["SubModName"].ToString() == "> Distribution Group")
                            {
                                //Response.Redirect(url);  
                                if (url.Contains("FinalRequestCompilation.aspx"))
                                {
                                    Response.RedirectToRoute(UrlRoute.RegisterRoutes(url));
                                }
                                else
                                { Response.Redirect(url); }
                            }
                            if (objsession["SubModName"].ToString() == "> Company Specialist Mapping")
                            {
                                //Response.Redirect(url);
                                if (url.Contains("FinalRequestCompilation.aspx"))
                                {
                                    Response.RedirectToRoute(UrlRoute.RegisterRoutes(url));
                                }
                                else
                                { Response.Redirect(url); }   
                            }
                            else
                            {
                                Response.Redirect("~/CommonSearch/CommonSearch.aspx");
                            }
                        }
                        else
                        {                                   
                               // Response.Redirect(url);
                            if (url.Contains("FinalRequestCompilation.aspx"))
                            {
                                Response.RedirectToRoute(UrlRoute.RegisterRoutes(url));
                            }
                            else
                            { Response.Redirect(url); } 
                        }
                    }
                    else
                    {
                        ClientScriptManager CSM = Page.ClientScript;
                        string strconfirm = "<script>alert('This functionality of EP has been temporarily deactivated. Contact Your Local Bits for more information.')</script>";
                        CSM.RegisterClientScriptBlock(this.GetType(), "Confirm", strconfirm, false);
                    }
                }
            }
        }
    }
    catch (Exception ex)
    {
        lblErrormsg.Text = ex.Message.ToString();
    }