In the picture here ( http://images.nikonians.org/galleries/showphoto.php/photo/388181/size/big/cat/22223 ), I used AF-S focused on the black line on the front round. I am not sure where sharp focus is. The distance was about 4 feet with 18-200mm lens set at 200mm. Where does the sharpest focus appear? I'm not sure. Looking at the rim at the bottom of the round on the right side of the second row, it appears to me that the focus is there.
Is there perhaps these there is too much reflection to make a determination?