Pixie did not get the pad training till around 5 or 6 months. I worked with her and never gave up and I never got angry at her. It is really figuring out your dog.
Once they realize what you want them to do they will do it, It just takes a lot of patience and perseverance.
Pixie even now at almost 8 months will have an accident if she gets excited and I don't remind her to go pee pee on her pad. Don't get angry just keep at it!!! Good luck~