CPU performance monitor counters cannot be read directly

Question

I tried to read directly from the PMCs instead of using Perf or something like that. The code is shown below. The full and compilable code is archived here

However, I failed. The 0x000000c0 should count the number of instructions retired. But I got a zero in the output.

Is there any error in my test and code?

#include <stdint.h>
#include <stdio.h>
#include "pmc.h"
#include <fstream>
#include <iostream>
using namespace std;
counter programmables[] =
{
  { 0x000000c0ull, "INSTRUCTION_RETIRED"},
};
int core = 0;
static void pin_cpu(size_t core_ID)
{
  cpu_set_t set;
  CPU_ZERO(&set);
  CPU_SET(core_ID, &set);
  if (sched_setaffinity(0, sizeof(cpu_set_t), &set) < 0) {
    printf("Unable to Set Affinity\n");
    exit(EXIT_FAILURE);
  }
}
int main(){
    pin_cpu(core);
    int result = 0;
    int n = 10000;
    double cnt = 0;
    srand(10769);
    size_t n_programmables = sizeof(programmables) / sizeof(programmables[0]);
    setup_pmc(core, programmables, n_programmables);
    zero_pmc(n_programmables);
    start_pmc();
    double a = 0;
    for(int i = 1;i <= n;i++){
        a = (double)(rand() + 300 + i)/(rand() - i);
        cnt += a;
    }
    stop_pmc();
    result = get_stats_single();
    printf("%lf %d\n",cnt,result);
}