can't Game Genie/patch codes on Gens to work

Currently using Gens emu to play some games (particularly PS II and IV). It has a cheat code feature where you can use game genie and patch codes (in which I assume its PAR), but it seems to never work. I've tried it for numerous games and they don't work. does GENS yet not support it or am i missng some files. I notice in some of the configs, I don't have a manual.exe under the config file section or a Genesis bios. I don't think they're related to this, but does anyone know whats wrong?

Gens emulator supports game genie/patch codes. To use it go to file then game genie and enter the codes. If this doesn't work then it's not the right code.