To be clear, the intended action is get recorder, talk to either of the guards, get a special dialog from Mezz that indicates he got the recording, and then go back and interact directly with the voice lock. Using the item itself won't do anything, it's just direct interaction with the hyena and then the lock. Should still work on the slut route (because obviously you still need to get through), but you may have managed to glitch the game somehow. If you keep having trouble getting any response from the hyena or the lock, I'd recommend trying from a save a little farther back if you've got it. And if you don't...too late now, but for future, ALWAYS rotate saves with RPGMaker games. After all this time GT is FAIRLY bug-free, but it can still act odd occasionally, and others aren't so forgiving.