Hi There!

I'm trying to get the Strange Key from Vito in the Domed City, but no matter how many times I talk to him, I can only end the conversation or trade with him. I've tried both options multiple times, but he won't give me the key. Does anyone know why this is? I know of the tunnel, but he should be giving me the key when talking to him. Thanks!

Update: I got it. I just had a finish a quest on the southern island first.