android - Firebase Database listeners not firing after a while while authenticated -

i'm making app , i've run problem firebase's database , authentication services.

after while, while authenticated (using firebase auth) , using app, database valueeventlisteners don't seem called, though there is data in database.

how i'm adding listeners:

firebasedatabase         .getinstance()         .getreference()         .child("my_child")         .addvalueeventlistener(new valueeventlistener()         {             @override             public void ondatachange(datasnapshot datasnapshot)             {                 log.d("app", "ondatachange");             }              @override             public void oncancelled(databaseerror databaseerror)             {              }         }); 

stuff i've tried:

• checking database rules (after relog reading fine - simulated reads pass while authenticated & unauthenticated)
• keepsynced(true) on databasereferences
• adding listeners in activity's oncreate instead of application's oncreate
• adding/removing/updating data in database trigger sync
• rebooting

any appreciated.

so, apparently issue api called "token service" not enabled in google apis dashboard.
helpful email firebase support (thanks guys!), i've turned on debug logging calling firebasedatabase.getinstance().setloglevel(logger.level.debug);

lo , behold: d/persistentconnection: pc_0 - error fetching token: internal error has occurred. [ �token service api has not been used in project <project-id> before or disabled. enable visiting https://console.developers.google.com/apis/api/securetoken.googleapis.com/overview?project=<project-id> retry.

so enabling api, seems have fixed error!