According to your username here on the site, it doesn't match up with the user you're trying to use. Your site username and in-game username are the same~ Have you tried using Aiko_Chan? Or are you using a different account for the roleplay?
If Ame88's solution doesn't work, maybe try using your old username instead? I know some for some people it's taken a day or two for the server to recognize that you've changed the name and still works if you use your old user.
Also I'm not sure if the "_" is a character that can be used with an in-game user. If that's the issue it may be the username itself!