无法使用Windows Phone后台任务调用服务器

Question

我有Windows Phone Silverlight 8.1的后台任务，只要我不需要访问互联网就可以正常工作。

以下是我尝试运行的代码：

var query = from photoTest2 in ParseObject.GetQuery("PhotoTest2")
                        where photoTest2.Get<string>("username") != "x"
                        select photoTest2;
            int resultsCount = await query.OrderByDescending("createdAt").WhereWithinDistance("location", point, ParseGeoDistance.FromKilometers(10)).CountAsync();

当我使用标准方法并在MessageBox中显示“resultCount”时，此方法运行正常，并且只需不到一秒钟。但是，作为后台任务，它只是无限期地停止。

这是后台任务的代码：

public sealed class FirstTask : IBackgroundTask
    {
        int resultsCount;

        public async void Run(IBackgroundTaskInstance taskInstance)
        {
            DateTime timeNow = DateTime.Now;
            TimeSpan minus28 = new TimeSpan(0, 28, 0);
            DateTime timeGone = timeNow.Subtract(minus28);

            BackgroundTaskDeferral deferral = taskInstance.GetDeferral();
            await GetCount();
            deferral.Complete();

            ToastTemplateType toastTemplate = ToastTemplateType.ToastText02;
            XmlDocument toastXml = ToastNotificationManager.GetTemplateContent(toastTemplate);
            XmlNodeList textElements = toastXml.GetElementsByTagName("text");
            textElements[0].AppendChild(toastXml.CreateTextNode("New Pictures!"));
            textElements[1].AppendChild(toastXml.CreateTextNode(resultsCount + " new images in your area"));
            ToastNotificationManager.CreateToastNotifier().Show(new ToastNotification(toastXml));


        }

        private async Task GetCount()
        {
            var point = new ParseGeoPoint(11.11, -11.11);
            var distance = new ParseGeoDistance(360);

            var query = from photoTest2 in ParseObject.GetQuery("PhotoTest2")
                        where photoTest2.Get<string>("username") != "x"
                        select photoTest2;
            resultsCount = await query.OrderByDescending("createdAt").WhereWithinDistance("location", point, ParseGeoDistance.FromKilometers(10)).CountAsync();

        }

非常感谢帮助：）