I can't even start the software because I can't back up my game save on my Action Replay Max Duo because unlike my other games, when I try to save it, it says there isn't a game in the cartridge slot. What do I do?
You probably own one of the earlier models. Newer models have pins 4 and 5 soldered. You can solder it yourself easily or just tape a small piece of aluminium foil between them so they make contact. I fixed mine this way and I can backup my Animal Crossing: Wild World game without any problems. Same goes for every other Nintendo Wi-fi Connection games (incompatible with earlier models) except for Pokémon Diamond/Pearl.