I want to train my lockpicking skills, and I've found Bantien's housein Talos Plaza, but I can't open the lock to get in. I did see him once before earlier in my game and spoke with him, but the trainer icon didn't appear. Can someone explain how I can get training from him? Thanks.
EDIT- I fond Malintus Ancrus, who is the other low-level trainer, but I don't have a training icon for him either. My skill in security is currently novice, so shouldn't I be able to train with these two? When I speak to them, there's no quest prompt that indicates I have to complete any task for them before they will train me.

Google "Oblvion wiki trainers" to check on when/where they'll train you. Like spell vendors they have their own routines and business places/hours.

Mara