null cookie upon redirecting from sandbox

[untech]

problem is that i am using paypal sandbox for testing purpose, whenever i redirect user to sandbox then i works fine, but upon return , it losses cookies and session too, i tried both , i am facing it for last 1 month but no progress, tried several forums but no help, First i used session, that works on everypage but not one the one to which sandbox is returning, i am using local host address and paypals successfully redirects back but losses session and cookie, here i am creating cookie\[code\]protected void Button1_Click(object sender, EventArgs e){ String employerEmail = Request.QueryString["employerEmail"]; HttpCookie employerEmailCookie = new HttpCookie("empEmailCookie", "defaulfCookieValue"); employerEmailCookie["employerEmail"] = employerEmail; employerEmailCookie["CurrentDate"] = DateTime.Now.ToString(); employerEmailCookie.Expires = DateTime.Now.AddMinutes(30); Response.Cookies.Add(employerEmailCookie); Response.Redirect("https://www.sandbox.paypal.com/us/cgi-bin/webscr?cmd=_xclick&[email protected]&item_name=MemberShip&amount=20&currenc y=USD&return=http://127.0.0.1:57135/Online%20Recruitment%20System-Final/paymentSuccessful.aspx?emailAdmin='"+employerEmail+"' &cancel_return=https://www.google.com/" );}\[/code\]and this is the page to which i am redirecting back but it always give, COOKIE is null\[code\]protected void Page_Load(object sender, EventArgs e){ Page.DataBind(); HttpCookie getEmployerEmailCookie = Request.Cookies["empEmailCookie"]; if (getEmployerEmailCookie!= null) { String employerEmail = Request.QueryString["emailAdmin"]; if (employerEmail == getEmployerEmailCookie.Value) { Response.Write("dear'" + getEmployerEmailCookie.Value + "',Your registration is successful"); } else { Response.Write("No payment made"); } } else { Response.Write("Cookie is null"); }}\[/code\]