Dividing by Three?

Well, though experimenting with the lastn="N" attribute I have concluded that, for some reason, my Movable Type build is dividing the "N" integer by approximately three. I was only able to get one day when I set lastn="3", but it displays seven days when I set lastn="21". I said "approximately" because the rule doesn't always work, for example I set lastn="14" and got five days of posts. I have no idea why my MT build it is doing this, it was fine before I upgraded from 3.14 to 3.2. Any ideas? Is Movably Type v3.2 not so good at math?