this may sound a little weird, but when i potty trained my two boys, i had them sit on the big potty backwards. little boys love to watch themself go and this way they didn't lean back to watch and spray the floor. or you could have him aim at fruit loops or a square of toilet paper. also try to reward him by making a big deal out of it: high fives, stickers, matchbox cars, ect... and not such a big deal out of when he doesn't go (though i understand how frustrating this can be since i have done it twice!). simply tell him "big boys go on the potty and wear big boy underpants. don't you want to be a big boy?" my oldest who is now five would kick and scream every time i tried to put the big boy underpants on him untill i put them in his pants one day when i was getting him dressed (without telling him), then when it came time to change his diaper or have him try to go to the bathroom, i took only his pants off. i made such a big deal out of him wearing underpants acting shocked and so proud he was laughing and forgetting to be scared about wearing something new! if nothing else works, maby he just isn't ready. don't loose hope though, no one goes to highschool still in diapers!