Is his crate too big? I know that this can be a problem if they learn that they can pee in one spot and go lie down in another spot. If this seems to be what he's doing, I'd get a smaller crate.
Also, remove the bedding and make him sleep on the plastic crate pan. My guess is that he's learned that he can pee his bed and not have to deal with the consequences of doing so because the bedding is soaking up the moisture and drawing it away from his body. Sometimes peeing on the cold hard crate pan and having to deal with it a few times is all it takes for them to figure out that keeping it clean is a much better idea.
Good luck!