Huawei HMS MLLocalTextAnalyzer with Transactor没有从摄像头流返回任何结果(Xamarin)

using Android.App;
using Android.Content.PM;
using Android.Hardware.Camera2;
using Android.OS;
using Android.Widget;
using Huawei.Hms.Ml;
using Huawei.Hms.Ml.Transactor;
using Java.Lang;

namespace XamarinHmsTextAnalyzer
{
    [Activity(Label = "XamarinHmsTextAnalyzer", MainLauncher = true, Icon = "@drawable/icon", ConfigurationChanges = ConfigChanges.ScreenSize | ConfigChanges.Orientation)]
    public class MainActivity : Activity
    {
        private CameraPreview mPreview;
        private MLLocalTextAnalyzer mAnalyzer;
        private MLTextAnalyzerTransactor mTransactor;

        protected override void OnCreate(Bundle savedInstanceState)
        {
            base.OnCreate(savedInstanceState);
            SetContentView(Resource.Layout.Main);

            if (ContextCompat.CheckSelfPermission(this, Manifest.Permission.Camera) != Permission.Granted)
            {
                ActivityCompat.RequestPermissions(this, new string[] { Manifest.Permission.Camera }, REQUEST_CAMERA_PERMISSION);
            }

            mAnalyzer = MLLocalTextAnalyzerFactory.Instance.GetLocalTextAnalyzer(new MLLocalTextAnalyzerSetting
            {
                Language = "en",
                OCRMode = MLOCRMode.STANDARD
            });

            mTransactor = new MLTextAnalyzerTransactor("your_transactor_id", "your_transactor_secret");

            mPreview = FindViewById<CameraPreview>(Resource.Id.camera_preview);
            mPreview.SetAnalyzer(mAnalyzer, mTransactor);
        }

        private const int REQUEST_CAMERA_PERMISSION = 200;
        public override void OnRequestPermissionsResult(int requestCode, string[] permissions, Permission[] grantResults)
        {
            base.OnRequestPermissionsResult(requestCode, permissions, grantResults);
            if (requestCode == REQUEST_CAMERA_PERMISSION)
            {
                if (grantResults.Length > 0 && grantResults[0] == Permission.Granted)
                {
                    // Permission granted, proceed with camera setup
                }
                else
                {
                    // Permission denied, show a message to the user
                }
            }
        }
    }
}