Facebook Integration Session Issue - facebook

Question

Here is my UserLogin.aspx Page code, which contains authentication of Facebook user, the problem is i am maintaing token in session which i laterly use it on Default.aspx. if you see the line Session["facebook_token"] = authToken;
On my Default.aspx page load i have placed this code, but it gives me null value, when i go to home or default page.
if (Session["facebook_token"] != null)
lblUserName.Text = Session["facebook_token"].ToString();
using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using SocialMediaModel;
using Facebook.Components;
public partial class UserLogin : System.Web.UI.Page
{
FacebookService _fbService = new FacebookService();
private const string FACEBOOK_API_KEY = "551810942508804";
private const string FACEBOOK_SECRET = "b63b8cca428b42935e6eab59976367b1";
protected void Page_Load(object sender, EventArgs e)
{
// ApplicationKey and Secret are acquired when you sign up for
_fbService.ApplicationKey = FACEBOOK_API_KEY;
_fbService.Secret = FACEBOOK_SECRET;
_fbService.IsDesktopApplication = false;
string sessionKey = Session["facebook_session_key"] as String;
string userId = Session["facebook_userId"] as String;
string authToken = Request.QueryString["auth_token"];
Session["facebook_token"] = authToken;
// We have already established a session on behalf of this user
if (!String.IsNullOrEmpty(sessionKey))
{
_fbService.SessionKey = sessionKey;
_fbService.UserId = userId;
}
// This will be executed when facebook login redirects to our page
else if (!String.IsNullOrEmpty(authToken))
{
_fbService.CreateSession(authToken);
Session["facebook_session_key"] = _fbService.SessionKey;
Session["facebook_userId"] = _fbService.UserId;
Session["facebook_session_expires"] = _fbService.SessionExpires;
}
// Need to login
else
{
Response.Redirect(#"http://www.facebook.com/login.php?api_key=" +
_fbService.ApplicationKey + #"&v=1.0");
}
}
}

Answer 1

string authToken = Request.QueryString["auth_token"];
Session["facebook_token"] = authToken;
Looks like you are executing these lines on every page load(?) – without checking if there even is a GET parameter by this name.