使用上下文菜单删除LongListSelector中的项目（隔离存储）？

Question

我刚刚编写了一个代码，用于通过使用上下文菜单删除LongListSelector的项目（保存在独立存储中）。但我遇到了有关在隔离存储中删除文件的问题。有些文件是从隔离存储中删除的，但有些文件没有（当我退出并重新打开应用程序时它就消失了）

这是我的事件句柄＆＃34; Delete_Click＆＃34;

 private void Delete_Click(object sender, RoutedEventArgs e)
    {
        MessageBoxResult message = MessageBox.Show("This recording will be deleted permanent.", "Delete!", MessageBoxButton.OKCancel);
        if (message == MessageBoxResult.OK)
        {         
            using (IsolatedStorageFile isoStore = IsolatedStorageFile.GetUserStoreForApplication())
            {
                var selectedSound = (sender as MenuItem).DataContext as SoundData;
                SpeakerLongListSelector.ItemsSource.Remove(selectedSound);


                // Delete selectedSound.FilePath                    
                if (isoStore.FileExists(selectedSound.FilePath))
                {
                    isoStore.DeleteFile(selectedSound.FilePath);
                }                                     

                // Remove the SoundData from App.ViewModel.CustomSounds
                App.ViewModel.CustomSounds.Items.Remove(selectedSound);

                // Save the list of CustomSounds to IsolatedStorage.ApplicationSettings
                var data = JsonConvert.SerializeObject(App.ViewModel.CustomSounds);
                IsolatedStorageSettings.ApplicationSettings[SoundModel.CustomSoundKey] = data;
                IsolatedStorageSettings.ApplicationSettings.Save();                    

                if (!isoStore.FileExists(selectedSound.FilePath))
                {
                    MessageBox.Show("This recording has been deleted successfully from your phone.");
                }
                else
                    MessageBox.Show("Sorry. Something went wrong.");

            }                           
        }