Game center - problem with lost session

Greetings, I’m working on my game and I want to integrate it with Google Play Game Center. I have one .lua file which has functions that are working with GPGC. This file looks like this:

----------------------------------------------------------------------------------------- -- -- gpgs\_manager.lua -- This class is used for Google Play Game Center ----------------------------------------------------------------------------------------- -- Your code here module(...,package.seeall); local gameNetwork=require("gameNetwork"); local loggedIntoGC = false local function initCallback(event)     if not event.isError then         loggedIntoGC = true         userInitiated = false         print("INIT CALLBACK SUCCESS");     else         print("INIT CALLBACK ERROR");         print("Error Code: ", event.errorCode)     end end local function loginListener(event1)         -- Checks to see if there was an error with the login.         if event1.isError then             print("THERE IS SOME ERROR");         else             print("SUCCESSFUL LOGIN");             loggedIntoGC = true;         end end local function achievementRequestCallback(event)     print("achievementRequestCallback"); end function returnGameNetworkState()     return gameNetwork.request("isConnected"); end function logoutFromGameNetwork()     gameNetwork.request("logout") end function loginToGameNetwork()     -- Tries to login the user, if there is a problem then it will try to resolve it. eg. Show the log in screen.     gameNetwork.request("login",{listener = loginListener,userInitiated = true}); end function initializeGPGC()     gameNetwork.init("google",initCallback) end function unlockAchievement()     myAchievement="CgkIstyY2-cKEAIQCA";     gameNetwork.request( "unlockAchievement",{achievement = { identifier=myAchievement, percentComplete=100, showsCompletionBanner=true },listener = achievementRequestCallback} ) end  

In my mainmenu.lua file I have button that calls loginToGameNetwork() which successfully logs me into GPGS. But when I change screen and go to level screen(using director:changeScreen(“level”,“fade”)) my

session is lost. Every time I call function  returnGameNetworkState() it returns me false.

Is there any way to save network session or is there some better way to do this? 

Thanks in advance!