Scheme中current-milliseconds无法刷新

Question

#lang racket
(define (runtime) (current-milliseconds))
(define (time-test n)
  (start n (runtime)))
(define (start n st)
  (if(>(remainder(* 116514698 4684494 8464168468486 646848648694 n)1234) 3)
     (reportt(- (runtime) st))
(define (reportt t)
  (display t))
(time-test 10)

输出始终为0，runtime没有刷新,环境是DrRacket