Error BCE0051 Operator '-'

Line(5,9)
Help please
aYUDA PORFAVOR ME DA ERROR


Blockquote
var vida = 100;

function QuitarVida (Dano : int) {

Vida -= Dano;
}

Blockquote
var Dano = 10;

function OnTriggerEnter (Fps : Collider) {

if (Fps.gameObject.tag == “Fps”){

   Fps.gameObject.SendMessageUpwards("QuitarVida",Dano,SendMessageOptions.DontRequiereREciver);

}
}

Code is case-sensitive. “Vida” and “vida” are not the same.