Julie gave some great advice!
I know how frustrating house-breaking can be...trust me. Carl wasn't reliable until AFTER he was a year old.
Preventing accidents is the best way to get through this obviously. Carl had so many accidents that we were never able to completely get the odor out of the carpet.
We got our carpet replaced after Mia was potty-trained (she was fully potty-trained by 6 months...thank God she was not difficult like her brother!) and it helped soo much!!
So ya know, just replace the carpet every time he has an accident.

Good luck!!!! He will catch on eventually, I promise! There is a light at the end of the tunnel!
(and apparently I'm over-tired...)