There is a problem with some flashcards such as the R4DS and all of its clones (M3 Simply, N5DS, ect) which limits the number of cheats that are displayed for games. This means that cheats for games that appear at the end of the cheat file are not displayed, this includes games for The World Ends With You, Yu-Gi-Oh, Trauma Center and others.

You have four options, the first is to get a new flashcard, the second is to delete the games from the cheat file you don't plan to use, the third option is to move the games to the top of the list and the fourth option is to use an alternate firmware/loader for your flashcard such as YSMenu, AKAIO and so on.

Before posting about games not having cheats in the forums, please check the GameList.txt file to see if the game really does have cheats.