nios10_1sp can not define structure to operate PIO?

this days i approch a promble that when using a structure in nios 10.1sp to operate pio,but i doesn't work at all. The details as flowing.

#define PIO_LED_BASE 0x101000

i define a structure for pio like this.

typedef struct{
 volatile unsigned long int DATA;
 volatile unsigned long int DIRECTION;
 volatile unsigned long int INTERRUPT_MASK;
 volatile unsigned long int EDGE_CAPTURE;
}LED_REG;

void led_reg_write(void)
{
 unsigned char i;

 for(i = 0; i < 8; i += 1){
  LED -> DATA = 1 << i;
  usleep(2000000);
 }
}

int main()
{
 while(1)
  led_reg_write();
}

my program is to shift the led one by one,but i doesn't work at all.

Is that a problem of the nios 10.1sp? Is there somebody met the same problem before?