OK I JUST GOT IT
Now I do not take credit for this as I read it somewhere else. My friend told me to re-install the Game & the Patch on another PS3 and then to log in to the multiplayer and the trophy might pop because it did for his friend. IT DIDN'T for me.......THE FIRST TIME..
I then read about re-installing the voucher code and this is what I did.
Now I think this only works with the limited edition..and to be safe use another or a friends PS3.
Install Crysis2 game data and the patch.
Once you have done that exit the game and go to the Playstation Store.
Go to Redeem Vouchers and re-enter the code you got with your limited edition.
It will automatically install.
Then exit the store and load up Crysis2.
Click on Multiplayer and once you in the multiplayer menu it should unlock.
It did for me and I am on level 47. Guys I hope this works for you as I know the frustration of Glitched Trophies.This method has worked for 1 of my other friends and did not for another 2.
I read somewhere else that playing a SP mission and then going back into multiplayer also works SOMETIMES??? All I know is that 4 people I know got glitched with this trophy this past weekend.
GOOD LUCK!