DownloadOperation回调未执行Windows Phone 8.1

Question

嘿大家我从msdn的后台下载转移中获取此代码，我稍微修改了一下

private async Task HandleDownloadAsync(DownloadOperation download, bool start)
{
    bool finish = false;
    try
    {
        LogStatus("Running: " + download.Guid, NotifyType.StatusMessage);

        // Store the download so we can pause/resume.

        activeDownloads.Add(download);
        DownloadData newData = new DownloadData();
        newData.DownloadOp = download;
        downloadData.Add(newData);
        Progress<DownloadOperation> progressCallback = new Progress<DownloadOperation>(DownloadProgress);
        if (start)
        {
            // Start the download and attach a progress handler.
            await download.StartAsync().AsTask(cts.Token, progressCallback);
        }
        else
        {
            // The download was already running when the application started, re-attach the progress handler.
            await download.AttachAsync().AsTask(cts.Token, progressCallback);
        }

        ResponseInformation response = download.GetResponseInformation();

        LogStatus(String.Format(CultureInfo.CurrentCulture, "Completed: {0}, Status Code: {1}",
            download.Guid, response.StatusCode), NotifyType.StatusMessage);
    }
    catch (TaskCanceledException)
    {
        LogStatus("Canceled: " + download.Guid, NotifyType.StatusMessage);
    }
    catch (Exception ex)
    {
        if (!IsExceptionHandled("Execution error", ex, download))
        {
            throw;
        }
    }
    finally
    { 
        finish = true;
    }

    if (finish == true)
    {
        //Something todo here
        activeDownloads.Remove(download);
        downloadData.RemoveAt(ind);
        finish = false;
    }
}

我在模拟器上尝试了这个并且在下载进度完成后立即执行了“finally”行，但是我在真实设备上尝试了这个并且没有执行finally行。它不会给出任何错误，并且在catch行上没有任何结果。