无法从unity3d中的firebase实时数据库检索数据

using Firebase;
using Firebase.Database;
using UnityEngine;

public class FirebaseDataRetrieval : MonoBehaviour
{
    private DatabaseReference databaseReference;

    private void Start()
    {
        // 获取Firebase实例
        FirebaseApp app = FirebaseApp.DefaultInstance;

        // 获取实时数据库引用
        databaseReference = FirebaseDatabase.DefaultInstance.RootReference;

        // 检索数据
        RetrieveData();
    }

    private async void RetrieveData()
    {
        // 异步获取数据
        DataSnapshot dataSnapshot = await databaseReference.GetValueAsync();

        // 处理返回的数据
        if (dataSnapshot != null && dataSnapshot.Exists)
        {
            // 遍历数据快照
            foreach (DataSnapshot childSnapshot in dataSnapshot.Children)
            {
                // 获取子节点的值
                string value = childSnapshot.Value.ToString();
                Debug.Log("Retrieved value: " + value);
            }
        }
    }
}