input key named : KeyCode.Escape is unkown

when a try to test my game it says "input key named : KeyCode.Escape is unkown" and i don't know why.

this is the code i used.

 var GUIEnabled : boolean = false;
 var autoSave : boolean = false;
 var paused : boolean = false;
         
 function Start() {
 OnLoad();
 if(autoSave == true) {
 autoSaveEnable();
 }
 }   
 
 function Update () {
 if(Input.GetKey("KeyCode.Escape") ) {
 GUIEnabled = !GUIEnabled;
 }
 
 if(Input.GetKey("KeyCode.Escape") && paused == false){
 paused = true;
 Time.timeScale = 0;
 }
 
 else if(Input.GetKey("KeyCode.Escape") && paused == true){
 paused = false;
 Time.timeScale = 1;
 }
 
 if(Input.GetKeyDown("p") && paused == false && GUIEnabled == false){
 paused = true;
 Time.timeScale = 0;
 }
 
 else if(Input.GetKeyDown("p") && paused == false && GUIEnabled == true) {
 paused = true;
 Time.timeScale = 0;
 }
 
 else if(Input.GetKeyDown("p") && paused == true && GUIEnabled == false) {
 paused = false;
 Time.timeScale = 1;
 }
 
 else if(Input.GetKeyDown("p") && paused == true && GUIEnabled == true) {
 paused = true;
 Time.timeScale = 0;
 }
 
 if(autoSave == true) {
 autoSaveEnable();
 }
 
 }
      
 function OnGUI () {
 if(GUIEnabled) {
 if (GUI.Button (Rect (Screen.width / 2,Screen.height / 2 - 40,105,20), "Save Data")) {
 OnSave();
 }
  
 if (GUI.Button (Rect (Screen.width / 2,Screen.height / 2 - 20,105,20), "Autosave True")) {
 autoSave = true;
 }
 
 if (GUI.Button (Rect (Screen.width / 2,Screen.height / 2 - 0,105,20), "Autosave False")) {
 autoSave = false;
 }
  
 if (GUI.Button (Rect (Screen.width / 2,Screen.height / 2 - -20,105,20), "Exit")) {
 GUIEnabled = !GUIEnabled;
 paused = false;
 Time.timeScale = 1;
 }
 }
 }
 
               
 function autoSaveEnable() {
 for(var x = 1; x>0; x++) {
 yield WaitForSeconds(1);
 Debug.Log("save me");
 OnSave();
 }
 }
 
 // a function created to save a game
  
 function OnSave(){
 PlayerPrefs.SetInt("CurXp", playerStats.curXp);
 PlayerPrefs.SetInt("MaxXp", playerStats.maxXp);
 PlayerPrefs.SetInt("CurHp", playerStats.curHp);
 PlayerPrefs.SetInt("MaxHp", playerStats.maxHp);
 PlayerPrefs.SetInt("CurMana", playerStats.curMana);
 PlayerPrefs.SetInt("MaxMana", playerStats.maxMana);
 PlayerPrefs.SetInt("Level", playerStats.level);
 
 }
 
 // a function created to load a game
  
 function OnLoad(){
 Debug.Log("loaded");
 playerStats.curXp = PlayerPrefs.GetInt("CurXp");
 playerStats.maxXp = PlayerPrefs.GetInt("MaxXp");
 playerStats.curHp = PlayerPrefs.GetInt("CurHp");
 playerStats.maxHp = PlayerPrefs.GetInt("MaxHp");
 playerStats.curMana = PlayerPrefs.GetInt("CurMana");
 playerStats.maxMana = PlayerPrefs.GetInt("MaxMana");
 playerStats.level = PlayerPrefs.GetInt("Level");
 
 }