Hello,
Many of us have faced the same exact issue, and it's solution is very easy.
1) You have to link your GamerTag for Xbox or your Playstation ID for PS2 or PS3 at https://profile.ea.com .
2) After that, you need to go to this link http://www.battlefieldbadcompany2.com/veteran and start entering your game codes so it can propagate to your veteran status.
Note: You need to logout of Battlelog and then back in so the Veteran status can show up.
However if you faced any issues while making any of these steps, don't be hesitate to contact the EA help at help.ea.com and they will square it out for you and you can also refer to this page for some more explanations about it http://veteran.battlefield.com/, have a nice day ahead .