I had a miniature Dachshund and he was never potty trained; they are very stubborn, and every Dachshund owner I know has had a rough time. I would just stay persistent, and if it continues you might want to try taking your pup to a behaviorist where they can tell you what your dogs strengths and weaknesses are to training, and how exactly to use those to help your dog and yourself. And remember, dogs react better to positive reinforcement, rather than negative.

Good luck!