[Admins]

a Keycode cannot be directly converted to character. I guess what you were trying to was conversion to and from ascii:

number = getascii("a") or getascii('a')
character = char(asciicode)

Often the key code is the same as ascii though (for a-z).
Also note that getascii() was bugged on serverside until a few days ago, I am not sure if the new npcserver has been uploaded to all machines yet.
keyname(0..10) is for knowing the name of the default game keys and works on clientside only.