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That's not how it works, that's what you would do with a dog, I guess. Rabbits are very different.
You don't really "litter train" rabbits, we just take advantage of a natural behaviour of liking to use a toilet spot. This behaviour emerges when they grow up, wouldn't expect it at 10 weeks.
What "litter training" is about is arranging their environment so that their instincts and our expectations are met, by designing and locating the litterbox where the rabbits will use them. Like, in a corner, or putting a hay rack there, they like to munch'n'poop. Also, the wasted hay becomes the litter, and for soaking up the urine and odor control a layer of wood pellets underneath works great.
You can help him accepting that spot by putting poops and soiled stuff in the box, and clean areas where he isn't supposed to do his business with vingar, or block those spots off. You'll need some patience, puberty can throw some sticks into that proceedure, so it can be "interesting" for months, depending on the individual rabbit.
