Spring boot @Transactional not working

I had @Transactional added for the service level method.

@Transactional(readOnly = false)
public void add(UserFollow uf){
    UserFollow db_uf = userFollowRepository.findByUserIdAndFollowUserId(uf.getUserId(), uf.getFollowUserId());
    if(db_uf == null) { 
        userFollowRepository.save(uf);      
        userCountService.followInc(uf.getFollowUserId(), true);
        userCountService.fansInc(uf.getUserId(), true);

        throw new RuntimeException();// throw an Exception
    }
}

      

        
        
        
      

    

userFollowRepository.save (UF); still persists crash, not rollback ...

i enable the transaction manager in the application.

@Configuration  
@ComponentScan 
@EnableAutoConfiguration  
@EnableJpaRepositories
@EnableTransactionManagement
public class Application {  

    @Bean
    public AppConfig appConfig() {
       return new AppConfig();
    }

    public static void main(String[] args) {  
       SpringApplication.run(Application.class);  
    }  
}  

      

        
        
        
      

    

i move @Transactional to control layer, it works, code:

@Transactional
@RequestMapping(value="following", method=RequestMethod.POST)
public MyResponse follow(@RequestBody Map<String, Object> allRequestParams){
    MyResponse response = new MyResponse();

    Integer _userId = (Integer)allRequestParams.get("user_id");
    Integer _followUserId = (Integer)allRequestParams.get("follow_user_id");



    userFollowService.add(_userId, _followUserId); //this will throw an exception, then rollback


    return response;
}

      

        
        
        
      

    

can someone tell me the reason, thanks!