Postive reinforcement is definitely the best. I think I would say "NO" and "Outside", if I caught him in the act. Rubbing the nose in it never has been proven to be effective.
Some just take a while. They're like children, not all will be trained at the same age, and not every dog responds to the same type of training. some are trained at 4 months, some take a year.
Some swear by crate training, I have never been able to keep mine confined to a crate. Some train to pee pads.
I have a doggie door, and have two 7 month old girls that are good most of the time, but do occasionally pee in the kitchen. They are confined to the laundry area with access to the doggie door for most of the day.
My 18 month olds are trained for the most part, but the male does want to lift his leg inside, occasionally.
I may not be able to help you, but we can complain about them together.
