Unity 5 Shader : Pulsing Emission range via scripting

Im trying to get a pulsing emission shader with a randomiser to mimic the effect of a candle inside an object. I created the shader already and it works but when I applying the following code to the object it turn purple when I press play.

56628-javascript-flicker.png

Here is the shader code:

I cant seem to access the EmissiveIntensity and change the range of it.

After some Tweaking, I finally managed to make it work using a Csharp script.

here it is (now just need to adjust the speed of the transitions):

void Start () {

}

// Update is called once per frame
void Update () {
	float random = Random.Range(0.5f, 1.5f);
	float intensity = Mathf.PerlinNoise(random, Time.time);
	gameObject.GetComponent<Renderer>().material.SetFloat("_EmissiveIntensity", intensity);
}

}

Emission range is not the same as intensity. Do to know how to change the former?