The very first logout code you get, the 14 digit code, is inputted when you go to the fifth icon (IR connection) and choose PC and then press A again to enter the password input screen. The second load, the Item codes, are from going to the fourth icon (Game/Activity) and choosing Password and pressing B again to enter the password input screen.
If that's what you did do, try typing your username and the letters in your password in capital letters. For example, instead of tmgc, try TMGC.
