CreateRoom failed.

I'm trying to create a room, but I'm having an error. Where is the problem?

 using Photon.Pun;
 using Photon.Realtime;
 using System.Collections;
 using System.Collections.Generic;
 using TMPro;
 using UnityEngine;
 
 public class Connect : MonoBehaviourPunCallbacks
 {
     [SerializeField] private GameObject connectingPanel;
     [SerializeField] private GameObject createRoomPanel;
     [SerializeField] private GameObject startGamePanel;
     [SerializeField] private GameObject adversaryPanel;
 
     [SerializeField] private TextMeshProUGUI mainServerText;
     [SerializeField] private TextMeshProUGUI mainUserText;
 
     [SerializeField] private TextMeshProUGUI otherServerText;
     [SerializeField] private TextMeshProUGUI otherUserText;
 
     [SerializeField] private TextMeshProUGUI infoServerText;
 
     private bool isConnecting = false;
 
     private const string gameVersion = "0.1";
     private const int maxPlayersPerRoom = 2;
 
     [SerializeField] int correntNumber = 0;
     public void CreateServer()
     {
         createRoomPanel.SetActive(false);
         connectingPanel.SetActive(true);
 
         isConnecting = true;
 
         PhotonNetwork.ConnectUsingSettings(gameVersion);
 
         CreateARoom();
 
     }
 
     public void CreateARoom() 
     {
         RoomOptions roomOptions = new RoomOptions();
         roomOptions.IsVisible = true;
         roomOptions.MaxPlayers = 2;
         PhotonNetwork.CreateRoom(mainServerText.text, roomOptions, TypedLobby.Default);
         correntNumber = 1;
     }
      public void JoinARoom()
     {
         PhotonNetwork.JoinRoom(mainServerText.text);
         correntNumber = 2;
     }
     public override void OnJoinedRoom()
     {
        
         int playerCount = PhotonNetwork.CurrentRoom.PlayerCount;
         Debug.Log(playerCount.ToString());
         if (playerCount != maxPlayersPerRoom)
         {
             infoServerText.text = "Waiting for the opponent...";
         }
         else
         {
             infoServerText.text = "You are connected!";
 
             if (correntNumber == 1)
             {
                 connectingPanel.SetActive(false);
                  startGamePanel.SetActive(true);
             }
             else if (correntNumber == 2)
             {
                 connectingPanel.SetActive(false);
                 adversaryPanel.SetActive(true);
             }
 
 
         }
     }
 
 }

Erro: CreateRoom failed. Client is on MasterServer (must be Master Server for matchmaking)but not ready for operations (State: ConnectingToNameServer). Wait for callback: OnJoinedLobby or OnConnectedToMaster.