Litter Training a kitten

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I have never had a problem with litter training any of my other cats- I showed them the litter box and they went. So now we just got two kittens- Dora and Diego and Dora doesn't seem to have trouble using the box but Diego is going to the bathroom everywhere else. What should I do to get him to go? He peed on our bed last night and our bed was SOAKED! Every time that he has pooped on the floor I have taken it and put it in the litter box. Then I put him in and make him cover it. He looks at me as if I am a retard then gets out and shakes the litter off of his paws! Does anyone have any suggestions about what we should do to help him learn where to go, preferably without having to lock them up somewhere to do it?