Fade Out problem

sorry i’m new in unity3d .i need a fade out texture of blood and i’ve try to istantiate it at the begin of the game with this code:

var tranparency : float = 0;
var textureColor : Color = guiTexture.color;
function Start()
{
time();
}

function time()
{

	while(true)
	{
	Debug.Log(textureColor.a);
	textureColor.a-=transparency;
    yield WaitForSeconds(1);
	}
}

but it don’t fade out…can someone help me?! i’ve lost much time for try this…

Color is a value type. It is not passed by reference, so when you assign textureColor to guiTexture.color, it just makes textureColor the same as your texture color.
Since you have access to guiTexture.color why not just always use it?

guiTexture.color.a -= transparency;