I am starting a toe-up sock, and am trying to understand the wrap and turn part. When I bring the yarn forward as if to purl, then slip the stitch, then move the slipped stitch onto the next needle and purl the next stitch, I end up with nothing that is wrapped at all! I just have that slipped stitch by itself and a purled stitch. That can't be right. I looked at pictures of it, but I still don't get it! Help!