NAT type help.

Hey, i got a problem, i forwarded all these port's
"Forward 13000 TCP; 1500, 3000, 3101, 28960 UDP"
but im still strict...
My nat type on my steam mw2 is open...
On alterIWnet it was open in the beginning,
but now it says strict, can someone explain to me why it is strict now?/

Help plz.

THX

You need to do these port´s TCP:27014-27050 UPD:1500, 3005, 3101, 27000-27030, 28960(you need to un-plug your router and the plug it back again i order to get it work)
but if it says strict and you want to host a game you will still be able to do that also if you want your friends to join