Still no Ding Dong (Doorbell Part 2)

It occurred to me today that I never followed up on my doorbell installation post. My reasoning for this is due to the fact that the doorbell is still not installed. I have been screwing around with the whole set-up for over a month now and I can't figure out (for the life of me) what is wrong with the system. The doorbell itself is perfectly fine. The buttons (front door and back door) are brand new, so I would assume they're fine as well. The transformer (also new) works like a charm. The wiring seems to be fine (when I test it with a low-voltage meter it has power). So, what the heck is the problem, then? I have literally tried everything.

I have to admit, I'm not totally convinced that the wiring is intact (I say this only because the lighted buttons I purchased won't light up when connected to the wires). But it doesn't matter anyway, because I don't have even the slightest clue how to repair the wiring , since it is completely inaccessible.

I probably should just give up and put the old wireless piece of crap back up. I don't know what else to do...