Hi Bill - sometimes it takes a LONG time for these small dogs to learn - you can't complain until he is 6 months old and even then he can have accidents sometimes.
We were told not to expect anything until our dog was a year and she wasn't 100% housebroken until then either.
It's got nothing to do with you or the dogs personality - it's because they are so small.
What you can do is this - every time he has eaten, played or slept you take him out for a walk of 30 minutes straight away (that's a lot of walking the first 6 months, but you'll be glad you did it). Bring small treats and every time he pees or poops praise him and give him a treat.
Small dogs pee a lot of times with a little amount, that's why the treats will have to be tiny.
I take my dogs paws and scratch the door every time I take them out - to teach them to scratch the door to get out. Someone suggested a smell bell next to the door that you ring every time you go out with dogs if you don't want them scratching the door.
There's a bonus to this:
Dogs are not challenged when they are asked to fetch a stick or run a mile. What really challenges it is using it's nose - and walking the dog so it can sniff the world will challenge it - and stimulate him
Good luck
