proteus8 LPC2114 定时器

求帮我看看为什么LED1是灭的，而不是一闪一灭的呢
#include #define  LED1  1<<7
unsigned int j;
void delayms(unsigned int ms)
{
      unsigned int i;
      while(ms--)
            for(i=0;i<125;i++);
}

void __irq tiMER0_ISR(void)
{
            if((IO0PIN&LED1)) IO0SET = LED1;
            else IOCLR0 = LED1;

            T0IR = 0x01;
            VICVectAddr0 = 0;

}

void TIMER0_intrrupt()
{
      T0TC = 0;
      T0PR = 99;
      T0MCR = 0X03;
      T0MR0 = 110592;
      T0TCR = 0X03;
      T0TCR = 0X01;
      VICIntEnable = (1<<4);
      VICIntSelect = 0x00;
      VICVectCntl0 = 0x24;
      VICVectAddr0 = (unsigned int)TIMER0_ISR;
}

int main(void)
{
      PINSEL0 = 0X00;
      IO0DIR = LED1|LED2;
      TIMER0_intrrupt();
      while(1)
      {

      }
}