Character Modifier Code Help?

I found the character modifying codes here for slot/neighbor one:
http://us.codejunkies.com/search/codes/cheat_codes.aspx?selp=17&game=&gameID=17825822&page=39

And for other slots/neighbor here:
http://www.supercheats.com/nintendods/animal-crossing-wild-world/2079/ar-codes/Neighbor-Modifier/

But... What does the "neighbor 1" and "neighbor 2" (and so on) mean?

Also, when I try to use these codes, they don't work...? I entered one (for Chevre! <3) into my Action Replay, but I didn't see Cherve anywhere in my town?

Thanks for the help!