应用程序可以'；t导航到主页

我的WP8.1 RT应用程序遇到了一个奇怪的问题——我的一位测试人员报告说，他在启动屏幕后看到了黑屏。该应用程序不会崩溃、挂断手机或其他情况——只是黑屏而不是主页。我在代码中实现了一些Trace方法来跟踪问题。代码如下：

// OnLaunched method that gets called when the App starts
protected async override void OnLaunched(LaunchActivatedEventArgs e)
{
    await Trace.WriteLineAsync(true, "Launched");
    Frame rootFrame = CreateRootFrame();
    await Trace.WriteLineAsync(true, "Before - better checkup");
    if (rootFrame.Content == null)
    {
        await Trace.WriteLineAsync(false, "Rootframe content was null, navigating");
        if (!rootFrame.Navigate(typeof(MainPage), e.Arguments))
            await Trace.WriteLineAsync(false, "Navigation false");
        else await Trace.WriteLineAsync(false, "Navigation was ok");
    }
    await Trace.WriteLineAsync(true, "After - better checkup");
    Window.Current.Activate();
} 
// Method creating the rootFrame:
private Frame CreateRootFrame()
{
    Trace.WriteLineAsync(true, "Create Root frame");
    Frame rootFrame = Window.Current.Content as Frame;
    if (rootFrame == null)
    {
        Trace.WriteLineAsync(true, "Root frame was null");
        rootFrame = new Frame();
        SuspensionManager.RegisterFrame(rootFrame, "AppFrame");
        rootFrame.NavigationFailed += OnNavigationFailed;
        Window.Current.Content = rootFrame;
        Trace.WriteLineAsync(false, "Window content {0}", Window.Current.Content.ToString());
    }
    return rootFrame;
}

测试人员得到的日志如下：

2014-10-06 13:02:56: Launched
2014-10-06 13:02:56: Create Root frame
2014-10-06 13:02:56: Root frame was null
Window content Windows.UI.Xaml.Controls.Frame
2014-10-06 13:02:57: Before - better checkup
Rootframe content was null, navigating
Navigation false
2014-10-06 13:02:57: After - better checkup
2014-10-06 13:03:01: App.cs suspending event

如您所见，最重要的行是Navigation false，这意味着

if (!rootFrame.Navigate(typeof(MainPage), e.Arguments))
     await Trace.WriteLineAsync(false, "Navigation false");

Navigation返回false-我无法在框架内导航，没有崩溃，没有挂起-（挂起事件有效），只是无法访问MainPage。我完全不知道问题的根源是什么。此外，在我的手机上，一切都正常，其他设备也正常；释放

有人知道我为什么不能导航到主页吗？

编辑-添加导航失败事件：

void OnNavigationFailed(object sender, NavigationFailedEventArgs e)
{
    Trace.WriteLineAsync(true, "Failed to load page");
    throw new Exception("Failed to load Page " + e.SourcePageType.FullName);
}