Taking Photo with Flash not working but Torch is Ok.

Question

Hi , I used below code to take photo.
1) The code work when I used the Torch light
2) problem:
 The same code cannot work when I used the Flashcontrol ( this is supported by the device).
 The Image is shown a brief moment , then the camera back to preview mode. But I have already disabled.
The code:
These are used:
   <Capture Element x:name="camera" />
   <image x:Name="preview">
 private async void TakePhoto(object sender, RoutedEventArgs e)
            try
                var bounds = Window.Current.Bounds;
                double height = bounds.Height;
                double width = bounds.Width;
                //-- create the source
                streamimage = new InMemoryRandomAccessStream();
                ImageEncodingProperties imageProperties = ImageEncodingProperties.CreateJpeg();
                //--capture the image
                 await m_mediaCaptureMgr.CapturePhotoToStreamAsync(imageProperties, streamimage);
                //-- <Capture Element x:name="camera" />
                camera.Visibility = Visibility.Collapsed;
                await m_mediaCaptureMgr.StopPreviewAsync();
                m_mediaCaptureMgr.Dispose();
                //--- create pic
                _bitmap = new BitmapImage();
                streamimage.Seek(0);
                await _bitmap.SetSourceAsync(streamimage);
                double d_imgW = _bitmap.PixelWidth;
                double d_imgH = _bitmap.PixelHeight;               
                //-- <image x:Name="preview">
                preview.Source = _bitmap;
                preview.Visibility = Visibility.Visible;
                preview.RenderTransform = new ScaleTransform() { ScaleX = zoom.ScaleX, ScaleY = zoom.ScaleY, CenterX = zoom.CenterX, CenterY = zoom.CenterY };
            catch (Exception ex)
Please help.
Thanks

Answer 1

Can someone help me? I just cannot get it to work! 
 When I use flashControl,
it just stop here :
   //--capture the image
   await m_mediaCaptureMgr.CapturePhotoToStreamAsync(imageProperties, streamimage);
Thanks