Once upon a time, there was a Player class

(simplified version)

enum animState{RUNNING,JUMPING,FALLING,IDLING};

class Player
{
public:
  Player(int x, int y);
  void handle();
  void show();
  ~Player();
private:
  int m_x;
  int m_y;
  animState playerAnimState;
}

There was also a "handle" function-member, which took care of all movement and collisions for the player:

#include "player.h"
void Player::handle()
{
  if(/*Player presses 'D' key*/)
  {
    m_x++;
    playerAnimState = RUNNING;
  } //Other stuff that is just there to look nice

Through lots of experimentation with "//" and "/**/", I've found that I consistently get an error at "playerAnimState = RUNNING." Have I broken some enumeration rule? Does my laptop really suck that bad? I hate to post a "fix my code for me" question, but I'm not very seasoned with enums.