Mystery Solved!

I finished the right half of the back of the tank this weekend. Once I actually sat down and got a groove on, it went by pretty fast. I also figured out why the back is knit in two halves. When I was initially buying yarn for the pattern, I noticed it said I needed nine buttons, but didn't see anywhere in the instructions another mention of buttons. I assumed it was a printing mistake. Then as I was finishing up the one half, I browsed the directions more carefully. The rest of the pattern instructions were hidden at the top of the following page! It just appeared as if they were part of the next pattern. The back buttons up, hence the two halves. Duh!