That's certainly an interesting dream. I'm not entirely sure what it means, it might make more sense if, in the dream, you were talking to someone to find that they're not there. I might be able to interpret that as a fear of being alone or something like that.

Perhaps there's something that you don't want to share with others, or there's a dark place in your mind and you're afraid that something else is there...

Try this one website for certain things such as cabinet, locked, and darkness. Dreammoods.com I tend to like this website for interpretations.