In my experience, most kids who refuse to go to school fall into one or more of these four categories:
Kids who are being bullied or those who are having trouble getting along with peers, either for the short term or the long term
Kids who are struggling academically and for whom school has become a very negative experience
Kids who have problems with authority and following the rules
Kids who are experiencing some anxiety—separation anxiety, (usually in younger kids), or worry about tests, what’s happening at home, or whether or not they’ll be picked up that day