UWP MediaCapture 拒绝访问相机

我正在尝试制作一个允许我拉起相机的项目，但我被告知每次程序运行时我都被拒绝访问相机。我通读了以下链接中的教程 https://msdn.microsoft.com/en-us/library/windows/apps/mt243896.aspx 并对代码进行了一些小的更改，但这些更改不应影响结果

    private MediaCapture _mediaCapture;
    private bool _isInitialized;
  private async Task InitializeCameraAsync()
    {
        if (_mediaCapture == null)
        {
            // Get available devices for capturing pictures
            var allVideoDevices = await DeviceInformation.FindAllAsync(DeviceClass.VideoCapture);
            // Get the desired camera by panel
            DeviceInformation cameraDevice =
                allVideoDevices.FirstOrDefault(x => x.EnclosureLocation != null &&
                x.EnclosureLocation.Panel == Windows.Devices.Enumeration.Panel.Back);
            // If there is no camera on the specified panel, get any camera
            cameraDevice = cameraDevice ?? allVideoDevices.FirstOrDefault();
            if (cameraDevice == null)
            {
                Debug.WriteLine("No camera device found.");
                return;
            }
            // Create MediaCapture and its settings
            _mediaCapture = new MediaCapture();
            MediaCaptureInitializationSettings mediaInitSettings = new MediaCaptureInitializationSettings {
                VideoDeviceId = cameraDevice.Id
              };
            // Initialize MediaCapture
            try
            {
                await _mediaCapture.InitializeAsync(mediaInitSettings);
                _isInitialized = true;
            }
            catch (UnauthorizedAccessException)
            {
                Debug.WriteLine("The app was denied access to the camera");
            }
            catch (Exception ex)
            {
                Debug.WriteLine("Exception when initializing MediaCapture with {0}: {1}", cameraDevice.Id, ex.ToString());
            }
            // If initialization succeeded, start the preview
            if (_isInitialized)
            {
                // Figure out where the camera is located
                if (cameraDevice.EnclosureLocation == null || cameraDevice.EnclosureLocation.Panel == Windows.Devices.Enumeration.Panel.Unknown)
                {
                    // No information on the location of the camera, assume it's an external camera, not integrated on the device
                    _externalCamera = true;
                }
                else
                {
                    // Camera is fixed on the device
                    _externalCamera = false;
                    // Only mirror the preview if the camera is on the front panel
                    _mirroringPreview = (cameraDevice.EnclosureLocation.Panel == Windows.Devices.Enumeration.Panel.Front);
                }
                await StartPreviewAsync();
            }
        }
    }

此外，我确保我的相机允许访问应用程序。有没有人知道为什么它不起作用？

await _mediaCapture.InitializeAsync(new MediaCaptureInitializationSettings
{
    StreamingCaptureMode = StreamingCaptureMode.Video 
});