I am trying to switch between scenes but it is not redirecting . Can anyone help with this?

 using System.Collections;
 using System.Collections.Generic;
 using UnityEngine;
 using Firebase;
 using UnityEngine.UI;
 using Firebase.Database;
 using Firebase.Unity.Editor;
 using UnityEngine.SceneManagement;
 
 public class Team : MonoBehaviour
 {
   public Text teamname;
 
   protected string userid;
 
     // Start is called before the first frame update
   public virtual void Start()
     {
       string flag="";
       FirebaseApp.DefaultInstance.SetEditorDatabaseUrl("API KEY/");
         DatabaseReference reference = FirebaseDatabase.DefaultInstance.RootReference;
         FirebaseDatabase.DefaultInstance.GetReference("Melinia/"+PlayerPrefs.GetString("userid")).GetValueAsync().ContinueWith(task => {
         if (task.IsFaulted) {
           // Handle the error...
           Debug.Log(task.Exception.Message);
         }
         else if (task.IsCompleted) {
           DataSnapshot snapshot = task.Result;
           Debug.Log(snapshot);
           flag="";
           foreach(var team in snapshot.Children) // rules
             {     flag=team.Value.ToString();
                   Debug.LogFormat("Key = {0}", team.Value);
             }
 
 
 
           // Do something with snapshot...
         }
       });
       if(flag.Length>1)
       {
 
         Debug.Log("ds");
  SceneManager.LoadScene(2);
       }
     }
 
 public void createTeam()
 {
   userid=PlayerPrefs.GetString("userid");
   DatabaseReference refer = FirebaseDatabase.DefaultInstance.GetReference("Melinia/"+PlayerPrefs.GetString("userid"));
   refer.Child("team").SetValueAsync(teamname.text.ToString());
   Debug.Log(PlayerPrefs.GetString("userid"));

 
 }
     // Update is called once per frame
     public void nextscene()
     {
       Debug.Log("dsfsffd");
 
     }
 }