puppy potty training, what am I doing wrong?

[beendointhisstuff]

4 month old puppy whom we've been attempting to potty train for almost 3 months. When we wake up in the morning we put him on the potty pad and tell him potty and he always does, but thats almost the only time. He almost always doesnt pee on it and I know he knows he's supposed to because sometimes he acually will. The weird thing is that sometimes he'll go less than a foot away from the pad. When he pees on the concrete we give him a tap on the butt and tell him in a stern voice "No" (the tap is not painful) Also when he was younger we had him go potty on newspapers, so is this maybe confusing to him? Any advice will help, thanks.