NullReferenceException: Object reference not set to an instance of an object

Questions & Answers
1

i keep getting the error nullreferenceexception and it also will not display the GUIs even though i have set the variables and the lifePercent variable seems to be functioning correctly. Any help on fixing the error and showing GUIs? (script worked perfect untill i added the section to draw the GUIs)

Health and GUI code-

var MaxHealth = 100;
var Health : int;

function Start ()
{
	Health = MaxHealth;
	onGUI();
}

function ApplyDamage (TheDamage : int)
{
	Health -= TheDamage;
	
	if(Health <= 0)
	{
		Dead();
	}
}

function Dead()
{
	RespawnMenuV2.playerIsDead = true;
	Debug.Log("Player Died");
}

function RespawnStats ()
{
	Health = MaxHealth;
}

var lifeRemainingBehindTexture : Texture;
var lifeRemainingTexture : Texture;
var lifePercent : float;

private var left : float;
private var top : float;
private var backgroundWidthLife : float;
private var lifeWidth : float;
private var height : float;

function onGUI()
{
	lifePercent = Health / MaxHealth;
	
	left = Screen.width / 2;
	top = 8;
	backgroundWidthLife = Screen.width / 4;
	lifeWidth = lifePercent * backgroundWidthLife;
	height = 12;
	
	//players health GUI drawing
	GUI.DrawTexture(Rect(left,top,backgroundWidthLife,height), lifeRemainingBehindTexture, ScaleMode.StretchToFill, true, 1.0);
	GUI.DrawTexture(Rect(left,top,lifeWidth,height), lifeRemainingTexture, ScaleMode.StretchToFill, true, 1.0);
}
2

Replace onGUI() with OnGUI(), and don’t call it from Start() (or from anywhere else!) - OnGUI is called automatically as required.