What's up with Killzone 2's sales?

[wanaraceu]

TsIT's doing well when comparing it to other games compare it to other games 2nd instalment. Eg look at COD 2. It sold around 2 mil by there 2nd one and now look at COD. By the time kz has realased a number 3 or 4 it should be doing around 4 mil I think.