NullReferenceException error

Whats wrong ?? Any help would be appreciated , thanks .

NullReferenceException: Obejcts reference not set to an instance of an object CharacterGenerator .DisplayVitals () ( at Assets/Charactersutff/CharacterGenerator.cs:49

using UnityEngine; using System.Collections; using System;

public class CharacterGenerator : MonoBehaviour { private PlayerCharacter _toon; private const int STARTING_POINTS = 350; private const int MIN_STARTING_ATTRIBUTE_VALUE = 10; private int pointsLeft;

 // Use this for initialization
 void Start () {
     _toon = new PlayerCharacter();
     _toon.Awake();
     
 pointsLeft = STARTING_POINTS;
     
 for(int cnt = 0; cnt < Enum.GetValues(typeof(AttributeName)).Length; cnt++) {
         _toon.GetPrimaryAttribute(cnt).BaseValue = MIN_STARTING_ATTRIBUTE_VALUE;
             }
 }
 // Update is called once per frame
 void Update () {
 
 }
 
 void OnGUI() {
     DisplayName();
     DisplayPointsLeft();
     DisplayAttributes();
     DisplayVitals();
     DisplaySkills();
 }
 
 private void DisplayName() {
     GUI.Label(new Rect(10, 10, 50, 25), "Name:");
     _toon.Name = GUI.TextArea(new Rect(65,10,100,25), _toon.Name);
 }
 
 private void DisplayAttributes() {
     for(int cnt = 0; cnt < Enum.GetValues(typeof(AttributeName)).Length; cnt++) {
         GUI.Label(new Rect(10,40 + (cnt * 25 ), 100,25 ) , ((AttributeName)cnt).ToString());
         GUI.Label(new Rect(115,40 + (cnt * 25 ), 30,25 ) , _toon.GetPrimaryAttribute(cnt).AdjustedBaseValue.ToString());        
      }
 }
 private void DisplayVitals() {
     for(int cnt = 0; cnt < Enum.GetValues(typeof(VitalName)).Length; cnt++) {
         GUI.Label(new Rect(10, 40 + ((cnt + 7 ) * 25), 100, 25), ((VitalName)cnt).ToString());
         GUI.Label(new Rect(115, 40 + ((cnt + 7 ) * 25), 30, 25), _toon.GetVital(cnt).AdjustedBaseValue.ToString());
      }
 }
 
 private void DisplaySkills() {
     for(int cnt = 0; cnt < Enum.GetValues(typeof(SkillName)).Length; cnt++) {
         GUI.Label(new Rect(250, 40 + (cnt * 25 ), 100,25 ) , ((SkillName)cnt).ToString());
         GUI.Label(new Rect(355, 40 + (cnt * 25 ), 30,25 ) , _toon.GetSkill(cnt).AdjustedBaseValue.ToString());
 }

} private void DisplayPointsLeft() { GUI.Label(new Rect(250, 10, 100, 25), "Points Left:" + pointsLeft.ToString()); } }