What's up with Killzone 2's sales?

[Khuutra]

makingmusic476 said:

I checked Ubisoft's sales for the week to see if even Haze is beating it. Haze didn't show up in the top 50, but GRAW2 for ps3 did, and it sold 3x as much as Killzone 2 last week in North America.

I don't understand it.

http://www.vgchartz.com/aweekly.php?date=40188&console=PS3&maker=Ubisoft&boxartz=2#

It's a ways down

398 copies, apparently