Same problem here. I've tried putting it in multiple times and it just keeps saying
The code you entered is not valid. Please try again. Please note that the code is in upper case to help identify Ls from 1s. For more information, contact Customer Support here.
Hay there, the code that its suposted to redeem in the site worked fine for me, but when i try to put the code in PSN to download the nuketown just dont work, says that is an invalid code or its already been used. PS: I typed everyting right.
I contacted my local GameStop about this issue. They told me to contact Activision directly because GameStop can't re issue codes. I've tried to call them all day long and it's been busy and I haven't been able to get through.
The Nuketown 2025 map code is in the box with the disc, pre order copies of the game should say "includes bonus Mao" on the case. Some people have been given the wrong copy with no code in the box, check amongst the booklet/flyers to see if it's there. If its no-where to be found you may have to take your copy back to be exchanged for the pre order copy. Hope that helps.
Tweeted Activision and here's the link to their response to me https://twitter.com/atviassist/status/268447706459013120
Good news though I did keep trying and eventually it did work but I must have tried about 20-30 times