Potty training


Hi! So my second son is 3. I’ve been trying to potty train him for over a year. He holds his pee all night. If I try putting him on the potty he refuses to go. We’ve tried reading, water activities, etc. while sitting on the potty. When he’s naked he won’t pee. But he will with a pull up on and training undies. Over and over. He absolutely refuses to go in the potty. He won’t even go in the bathtub or outside… I’m at a loss. Any advice?