why won't this work, m_flags doesn't work

Flagger.h

#ifndef _FLAGGER_H
#define _FLAGGER_H

#include <stdint.h>
#define MAX_NUM_FLAGS 8


struct Flag_info{
  uint8_t id;
  uint16_t trig_count;
  uint8_t flag_state;
};

class Flagger
{
  public:
    Flagger(){
      for (int i=0; i<MAX_NUM_FLAGS; i++){
        m_flags[i].id=0;  
        m_flags[i].trig_count=0;  
        m_flags[i].flag_state=1;  
      }   
    m_num_flags=0;
    m_max_flags=MAX_NUM_FLAGS;
    };  

    uint8_t registerFlag(uint16_t trig_count){
      m_flags[m_num_flags].id=m_num_flags;  
      m_flags[m_num_flags].trig_count=trig_count; 
      m_flags[m_num_flags].flag_state=0;  
      m_num_flags++;
    }   

    uint8_t getFlag(uint8_t id){
      return m_flags[id].flag_state;
    }
   
  private:
    Flag_info m_flags[MAX_NUM_FLAGS];
    uint8_t m_num_flags;
    uint8_t m_max_flags;
};

#endif

g++ Flagger.cpp -o testFlag

it works now...