Just keep persevering, but don't force things. Kids are all different and reach milestones at different ages and in different ways. Don't stress it, he'll get there.

I’m a big believer in offering opportunities but not pushing. My son is 2.5 and knows when he needs to wee or poo but has little desire to use the potty or toilet. When he is having nappy free time we offer the opportunity and ask him if he would like to go but he very rarely does. We just talk about it in a positive way, read stories that include children using the toilet and make it a positive thing. When they are ready it will click into place.