China DOS Union

Why can't the interrupt respond in this program? Which expert can help me solve it, my QQ: 19684802, Email: zhanghuaben@yahoo.cn
#include "graphics.h"
#include "stdio.h"
#include "fcntl.h"
#include "stdlib.h"
#include "alloc.h"
#include "stdlib.h"
#include "dos.h"

#define LOW_BYTE(n) (n&0x00ff)
#define HI_BYTE(n) ((n>>8)&0x00ff)÷

// Variables used by the spindle
union{
unsigned int b;
unsigned char d[2];
}MAxisCnt;

void SetXMotTimer(unsigned count)
{
outportb(0x3e7, 0xb0);

outportb(0x3e6, LOW_BYTE(count));
outportb(0x3e6, HI_BYTE(count));
}

void interrupt XMotorInt(void)
{
disable();

SetXMotTimer(1000);
......//Output pulse signals to the IO port
outportb(0x20, 0x20);

enable();
}

void main(void)
{
outportb(0x3eb, 3);

outportb(0x21, 0);

setvect(11, XMotorInt);

SetXMotTimer(1000);

getch();

return;
}

I'm also encountering a problem similar to the poster's. May I ask how the poster finally solved it?