So right down to the nitty gritty,

I have a 92 sonoma 2.8, recently my left turn signal flasher would just stay on and I saw the smaller "middle" bulb was burnt out in the back driver side. So I replace that. Flasher still doesn't flash.. So I change the signal switch. Now the flasher flashes, front signals work fine but rear signal doesn't signal, nor does the brake light come on, But when I turn on my head lights the bulbs light up fine. But they still do not signal. I'm stumped now guys, any thoughts?