If your 3DS unit literally doesn't detect the card (blank slot in the home menu) it may be contact issues. See http://gbatemp.net/topic/231412-solving-acekard-contact-issues/ for tips on how to remedy this.
If your 3DS unit does display your cartridge when you insert it (Danny Phantom, Alex Rider, a Japanese game by DORASU*, Chessmaster) and has the error as described on the wiki page Another World linked for you, please read into that further.
The currently compatible bootloader for AK2i is a Japanese Hello Kitty game by DORASU, and the icon is a little black, white, and red ribbon bow.
*I don't remember what the icon looked for the previous, obsolete bootloader that was also taken from a Japanese DORASU game.