FormsAuthenticationTicket is Null

Using Framework 4.0
Scenario 1:
   Signed in using LiveSite.com.
   In LiveSite.com FormsAuthenticationTicket is not null & ticket.name is my UserID.
   In LocalSite.com FormsAuthenticationTicket is null.
   I dont know what goes missing here.
Scenario 2:
   Signed in using LocalSite.com.
   In LocalSite.com FormsAuthenticationTicket is not null & ticket.name is my UserID.
   In LiveSite.com FormsAuthenticationTicket is null.
My Machine config settings is same in Local & Live sites
Target Framework is 4.0
ApplicationAuthenticate_request is below:
HttpCookie AuthCookie = Request.Cookies[FormsAuthentication.FormsCookieName]; FormsAuthenticationTicket ticket = null; if (AuthCookie != null) { ...