You should join the Y.O.M.I Modding server and read #getting-started if you havent done that already,gives you a pretty quick and easy explanation on how to mod your game,also always make sure you have the "enable mods" option checked ingame,that you have char-loader installed(all characters require it),keep the game stored in the C: drive and that your mods are on .zip files. If all of this fails/you have already tried you should ask a helper in the Yomi modding server for help