Facebook graph leaderboard doesn't update immediately

Hi guys, I’m creating a Facebook leaderboard but I have some problems when I update it. When I update the facebook score and then open the leaderboard, it shows me the old score. If I close the game and I oped the game again, it shows the correct leaderboards. What am I doing wrong? Here the code:

function fClassificaFb(event)     if event.phase == "began" then                 bpClassificaFb.isVisible = true     end     if event.phase == "moved" then         bpClassificaFb.isVisible = false     end     if event.phase == "ended" then         bpClassificaFb.isVisible = false         fbAggiornaClassifica()         timer.performWithDelay(150, fbVisualizzaClassifica, 1)     end end function fbVisualizzaClassifica(event)     local status = network.getConnectionStatus()     if status.isConnected then         facebook.login(appID, fbListener)     else         fbAlert = native.showAlert("Errore di connessione", "Non è stata rilevata alcuna connessione a Internet.", {"Annulla", "Riprova"}, fbReLogin)     end end function fbAggiornaClassifica()     local status = network.getConnectionStatus()     if status.isConnected then         facebook.login(appID, fbListenerAggiorna)     else         fbAlertAggiorna = native.showAlert("Errore di connessione", "Non è stata rilevata alcuna connessione a Internet.", {"Annulla", "Riprova"}, fbReLoginAggiorna)     end end function fbListener(event)     if "session" == event.type then         if "login" == event.phase then             access\_token = event.token             facebook.request(appID.."/scores")         end     elseif "request" == event.type then         local response = json.decode(event.response)         myData.dataFriends = response.data         storyboard.gotoScene("classifica\_facebook")     end end function fbListenerAggiorna(event)     if "session" == event.type then         if "login" == event.phase then             access\_token  = event.token                 if storyboard.state.punteggio \> myTable.highScore then                     myTable.highScore = storyboard.state.punteggio                 end                 loadsave.saveTable(myTable, "myTable.json")                 local attachment = {                     score = tostring(myTable.highScore)                 }                 facebook.request("me/scores" , "POST", attachment)         elseif "request" == event.type then         end     end end