Error : Object reference not set to an instance of an object body.Update

My unity is with the following problem:

NullReferenceException: Object reference not set to an instance of an object
body.Update() (at Standard Assets/Assets/Menu/corpo.js: 20)

Tags and some elements as in Portuguese of Brazil

#pragma strict
var Vida: float;
var TVida : TextMesh;

var TempoQueda: float;

function Start () {
Vida = 100;
TempoQueda=-1;
}

function Update () {

if (TempoQueda>=0)
{
TempoQueda += Time.deltaTime;
}

TVida = transform.GetComponentInChildren(TextMesh);
TVida.text = "Vida: "+Vida;



}
var testeInpacto : Vector3;
function OnCollisionEnter(collision: Collision)
{
  testeInpacto = collision.impactForceSum;
  if (testeInpacto.y<10)
  {
    if (collision.transform.tag!="agua")
    {
      if (TempoQueda>1)
      {
       Vida = Vida - (100 * (TempoQueda/3));
      }
    }
  }
  TempoQueda=-1; 
}


function OnCollisionExit(collisioninfo : Collision) {

TempoQueda = 0 ;


}

NullReferenceException mean : you are trying to access a NULL Object (var TVida : TextMesh;), you cannot access that object because he is null :slight_smile: you need to instantiate the TVida object or assigned to not null value :slight_smile: