I dont understand!

i have been trying to sign up for a korean warrock account and finally got to the end and this error message came up!

아이디에는특수문자를사용할수없습니다

could anyone tell me what this means?

btw i hve tried a translator and it come up with, "To child D it will not be able to use a special letter"

could someone please help

u have to check ur niick name -.-

edit:no sorry, its that u have illegal characters OR ur name is allready taken -.-