Maybe because it considers single letters as advanced shortcuts? Just a guess ...

thx for Reply

I've read this article http://forums.opera.com/post/57164
it teached to edit Preferences in Opera\profile\data\ to setup shoutcut
but when i set like this

"Keybindings": {
"Basic": {
"NavigateDown": [ "J" ]
}
}

[J] isn't work
what's wrong with it? O.O