i cant fix the error BCE0023?!!!!

Hi,
I am new to coding and i cant solve this error(Assets/Inventory/Inv.js(23,74): BCE0023: No appropriate version of ‘UnityEngine.GameObject.GetComponent’ for the argument list ‘(GUISurvival)’ was found.) I am creating an inventory and am linking it to my player stats. Here are my scripts:
Inv.js:

var menuSkin : GUISkin;

var wood : int= 0;
var stone : int=0;
var rope : int=0;

var food : int=0;

var water : int=0;

var bandage : int=0;

private var showGUI : boolean = false;

private var GUISurvival : GUISurvival;

var minimumVal : int = 0;

function Start()
{
    GUISurvival = GameObject.Find("First Person Controller").GetComponent(GUISurvival);
}


function Update()
{

    if(wood <= 0)
    {
      wood = minimumVal;
    }

    if(rope <= 0)
    {
      stone = minimumVal;
    }

    if(rope <= 0)
    {
      rope = minimumVal;
    }

    if(food <= 0)
    {
      food = minimumVal;
    }

    if(water <= 0)
    {
      water = minimumVal;
    }

    if(bandage <= 0)
    {
      bandage = minimumVal;
    }

    if(Input.GetKeyDown("e"))
    {
      showGUI = !showGUI;
    }

    if(showGUI == true)
    {
    Time.timeScale = 0;
    GameObject.Find("First Person Controller").GetComponent(FPSInputController).enabled = false;
    GameObject.Find("First Person Controller").GetComponent(MouseLook).enabled = false;
    GameObject.Find("Main Camera").GetComponent(MouseLook).enabled = false;
    }

    if(showGUI == false)
    {
    Time.timeScale = 0;
    GameObject.Find("First Person Controller").GetComponent(FPSInputController).enabled = true;
    GameObject.Find("First Person Controller").GetComponent(MouseLook).enabled = true;
    GameObject.Find("Main Camera").GetComponent(MouseLook).enabled = true;
    }
 }

 function OnGUI()
 {
     if(showGUI == true)
     {
          GUI.skin = menuSkin;
              GUI.BeginGroup(new Rect(Screen.width / 2 - 150, Screen.height / 2 - 150, 300, 300));
                  GUI.Box(Rect(0, 0, 300, 300), "Inventory");

                  //Resources Collected
                  GUI.Label(Rect(10, 50, 50, 50), "Wood");
                  GUI.Box(Rect(60, 50, 20, 20), "" + wood);

                  GUI.Label(Rect(90, 50, 50, 50), "Stone");
                  GUI.Box(Rect(130, 50, 20, 20), "" + stone);

                  GUI.Label(Rect(170, 50, 50, 50), "Rope");
                  GUI.Box(Rect(200, 50, 20, 20), "" + rope);



                  //Usable items
                  GUI.Label(Rect(10, 190, 50, 50), "Food");
                  GUI.Box(Rect(60, 190, 20, 20), "" + food);
                  if(GUI.Button(Rect(100, 190, 100, 20), "Eat Food?"))
                  {
                       food--;
                       Eat();
                  }

                  GUI.Label(Rect(10, 210, 50, 50), "Water");
                  GUI.Box(Rect(60, 210, 20, 20), "" + water);
                  if(GUI.Button(Rect(100, 210, 100, 20), "Drink Water?"));
                 {
                       water--;
                       Drink();
                 }

                 GUI.Label(Rect(10, 240, 50, 50), "plaster");
                  GUI.Box(Rect(60, 240, 20, 20), "" + bandage);
                  if(GUI.Button(Rect(100, 240, 100, 20), "Heal?"));
                 {
                       bandage--;
                       Heal();
                 }
                 GUI.EndGroup();
      }
  }   

function Eat()
{
   GUISurvival.currentHunger += 20;
}

function Drink()
{
   GUISurvival.currentThirst += 20;
}

function Heal()
{
   GUISurvival.currentHealth += 20;
}  



-------------------------------------------------------
-------------------------------------------------------

GUISurvival.js:

function Update()
{
	if(currentHealth <= 0)
	{
		CharacterDeath();
	}
	
	/* THIRST CONTROL SECTION*/
	
	//Normal thirst degredation
	if(currentThirst >= 0)
	{
		currentThirst -= Time.deltaTime / 2;
	}
	
	if(currentThirst <= 0)
	{
		currentThirst = 0;
	}
	
	if(currentThirst >= maxThirst)
	{
		currentThirst = maxThirst;
	}
	
	/* HUNGER CONTROL SECTION*/
		if(currentHunger >= 0)
	{
		currentHunger -= Time.deltaTime / 4;
	}
	
	if(currentHunger <= 0)
	{
		currentHunger = 0;
	}
	
	if(currentHunger >= maxHunger)
	{
		currentHunger = maxHunger;
	}
	
	/* DAMAGE CONTROL SECTION*/
	if(currentHunger <= 0 && (currentThirst <= 0))
	{
		currentHealth -= Time.deltaTime / 2;
	}
	
	else
	{
		if(currentHunger <= 0 || currentThirst <= 0)
		{
			currentHealth -= Time.deltaTime / 4;
		}
	}
}

function CharacterDeath()
{
	Application.LoadLevel("SimpleMenu");
}

function OnGUI()
{
	//Icons
	GUI.Box(new Rect(5, 30, 50, 23), "Health");
	GUI.Box(new Rect(5, 55, 50, 23), "Thirst");
	GUI.Box(new Rect(5, 80, 50, 23), "Hunger");
	
	//Health / Hunger / Thirst bars
	GUI.Box(new Rect(55, 30, barLength, 23), currentHealth.ToString("0") + "/" + maxHealth);
	GUI.Box(new Rect(55, 55, barLength, 23), currentThirst.ToString("0") + "/" + maxThirst);
	GUI.Box(new Rect(55, 80, barLength, 23), currentHunger.ToString("0") + "/" + maxHunger);
	
}

Instead of

private var GUISurvival : GUISurvival;

write

private var guiSurvival : GUISurvival;

And also,

guiSurvival = GameObject.Find("First Person Controller").GetComponent(GUISurvival);

If you still get the error try

GetComponent.<GUISurvival>();

Making sure your GUISurvival script is attached to your gameObject.