How to save a file after selected it with FileOpenPicker c#

Question

I using windows phone silverlight and when run the code in the instruction "StorageFile file = await fileOpenPicker.PickSingleFileAsync();" it generates an exception "The request is not supported", I have already consulted the guide on how to keep an app after calling a method of selecting the file, but it seems that this is only for Windows Phone RunTime.

 

Does anyone know how can I do?

 

This is the code:

 

private async void btn_Crea_Click(object sender, RoutedEventArgs e)

{

    FileOpenPicker openPicker = new FileOpenPicker();

    openPicker.ViewMode = PickerViewMode.Thumbnail;

    openPicker.SuggestedStartLocation = PickerLocationId.VideosLibrary;

    openPicker.ContinuationData["Operation"] = "UpdateVideo";//"UpdateProfilePicture";

    openPicker.FileTypeFilter.Add(".3GP");

    openPicker.FileTypeFilter.Add(".MP4");

    openPicker.FileTypeFilter.Add(".WMV");

    openPicker.FileTypeFilter.Add(".AVI");

    openPicker.FileTypeFilter.Add(".MOV");

    openPicker.FileTypeFilter.Add(".3G2");

    openPicker.PickSingleFileAndContinue();

->StorageFile file = await openPicker.PickSingleFileAsync(); // file represents the video selected by user <-

    if (file != null)

   {

     // Open a stream for the selected file

     Windows.Storage.Streams.IRandomAccessStream fileStream =

                     await file.OpenAsync(Windows.Storage.FileAccessMode.Read);

    // Set the video file

   Singleton.Instance.video = file; // save a video file in the singleton for future use

  }

}