Thought I'd chime in since I have already knit the groovy sweater dress. In the small, it is not possible to decrease to the 28 and have the top "vine come out of the center of the two knit stitches. It is an error in the pattern according to an email I got from someone at Classic Elite.
One more thing I want to mention is about the sizing. I am a size 4 or 6 (5'7'' 120 pounds) and I made the small. I have worn it and feel the top is too tight to be comfortable. Also I don't like it if the knitting looks too stretched out. That is just my personal opinon. I think I am going to rip out the top and start again from the ribbing and make the top part a medium. I will be doing the sleeves short sleeve and wear a very thin long sleeve shirt under it.