firstly ive got to say this is a joke crytek
firstly how the hell can you release a dlc and not tell the people that are keeping you in business how to actually redeem it and then load it.especially as we have to move it from one folder to another.

there has been a lot of problems for people trying to load it the normal way so if that hasnt worked for you here is a work around.

ok down to business.

1. You have to buy DLC in-game.
2. It will send you to gamesas to add a credit/debit card (no paypal available)
3. After payment go to http://www.gamesas.com/redeemcode/
4. Click Purchase History on top left
5. Click on dlcpack1.zip next to "Crysis 2 Map Pack 1" and download 116MB file
the zip will download to my downloads folder.

(now the fun begins)
do not open the zip file as it will corrupt it.
you now have to find your crysis 2 folder in saved games folder.
im using vista and the folder is stored in:
start > click on your name at top > click on saved games > crysis 2 > dlc (this will be empty) > and drag whole zip file from your download folder into the dlc folder.
close and restart.

that has worked for quite a few people.

if the above does not work the final option is this:
ive uploaded the zip file to an external server.
send me a pm and i will send you the link to download it.
then like above you drag zip file to crysis 2 folder and that should work.

Personally I had no problem. It all went as it should.
Added my card details on the gamesas site, started the game, purchased and downloaded. Was expecting a fuss but got none.

lucky you. there are lots of players unable to load the dlc especially when they purchased the main game from steam.