“隔离存储无法确定应用程序商店的程序集”异常

Question

尝试运行以下代码时，我收到此异常（标题）：

   public static String WriteSettings(String fileName, String settings)
    {
        try
        {
            using (IsolatedStorageFile settingsStore = IsolatedStorageFile.GetStore(IsolatedStorageScope.Assembly | IsolatedStorageScope.User, null))
            {
                using (StreamWriter writer = new StreamWriter(new IsolatedStorageFileStream(fileName, FileMode.Create, settingsStore)))
                {
                    writer.Write(settings);
                }
            }
        }
        catch (Exception e)
        {
            return "Cannot save settings. The following error has occurred: " + e.Message;
        }

        return "Settings saved";
    }

发生异常的行是：

using (IsolatedStorageFile settingsStore = IsolatedStorageFile.GetStore(IsolatedStorageScope.Assembly | IsolatedStorageScope.User, null))

任何帮助都非常感谢!!