Board Thread:Friend Code Exchange/@comment-26013388-20150116193618/@comment-24668482-20150116201947

The codes only work 4-5 times, after that they expire and will give anyone who tries them that "you have entered an incorrect code" message. Just one of those annoying things. If you see a code that doesn't work you could reply and let the poster know their code has expired and they need to post a new one (and leave your code for them if you like). That would also help the next person looking know that that code is gone to save them trying. Some people post their code on multiple sites, so they expire very, very quickly. Sometimes the best thing to do is just start your own thread with your own code and then keep checking the code in your game to see if a new one has been generated (meaning the old one has expired) and updating it in that thread.

Another thing to wach out for since people don't post their game names here that often - you will get that exact same error message if you are already friends with that person. You will also get it if you type in the code incorrectly.