Windows phone 8 如何在windows phone c中保存图片照片时删除媒体库

从媒体库中删除图像时，出现访问被拒绝错误。 这是我的密码

using (MediaLibrary _MediaLibrary = new MediaLibrary())
{
    foreach (PictureAlbum album in _MediaLibrary.RootPictureAlbum.Albums)
    {
        if (album.Name == "Saved Pictures")
        {
            PictureCollection Pictures = album.Pictures;
            foreach (Picture _Picture in Pictures)
            {
                if (_Picture.Name.Contains("Tattoo_" + FavoritesName))
                {
                    File.Delete(_Picture.GetPath());
                }
            }
    }
}

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无法从媒体库中删除图片。我猜是某种安全约束