if he's not in server, I cant ban him.. can I? :O
I didn't think I could use the admin window and edit IDs...
He doesnt necessarily have to be in the server to ban him, but he has to have visted the server. If he came and left, his name and ID will be displayed on the
Clear Bricks menu, so you can just find his name there, highlight it, and ban him via. the menu's ban button.
If he isn't on the server or he hasent even visited it in the first place, then you will have to ban him via. that command, like you already did.