Be sure that when you go out, you go to the EXACT same spot where he peed the first time. We learned how valuable that tip was right away. They will always go back to their spot. As ours also did in the house on the carpet, when he was a puppy. Also, I would recommend taking him out every hour, not every two. We had to do that for a while until he was able to gain better control of his bladder. But taking him out to the same spot is very important, because if he doesn't smell it, and he is somewhere else, he may not go. We had to take ours out once a time during the middle of the night. He would make it from then until morning. And be sure to cut off the water a hour or so before bedtime. Good luck. It is very frustrating in the beginning, but it will get better. Our 8 month old can now go all day while we are at work until we get home without any trouble.
:)