JoinOrCreateRoom failed

Hello,
I am using PUN Free with Unity Pro for my IOS game powered by Unity. Roughly my code pseudo code is like that:

in Awake method: PhotonNetwork.ConnectUsingSettings (string gameVersion);
in StartRandomMatch method:
RoomOptions roomOptions = new RoomOptions(){isVisible = true, maxPlayers = 2};
PhotonNetwork.JoinRandomRoom(string roomName, roomOptions, TypedLobby.Default);
(when i Debug.Log my PhotonNetwork.connected, I get 'true')

OnJoinedLobby, OnPhotonRandomJoinFailed, OnJoinedRoom events are also called (for now i have not implement anything in these events except that PhotonNetwork.CreateRoom(null) is called in OnPhotonRandomJoinFailed).

I get "JoinOrCreateRoom failed. Client is not on Master Server or not yet ready to call operations. Wait for callback: OnJoinedLobby or OnConnectedToMaster." log when i run project. This log appears on both Unity run or XCode run after IOS build in Unity.

Is it because i am trying to implement my game on IOS platform? Or what is it about? Also, even if it works fine how my game will work on IOS by using Game Center (i.e. finding random player on Game Center or make me invite friends/accept invitations on Game Center)? Please inform and enlighten me :roll: