Why can't I reference Graphics Raycaster in my gameObject?

I am trying to get a reference to the Graphic Raycaster on my Canvas so that I can enable/disable it. This is what I am doing:

shopCanvas.GetComponent<GraphicRaycaster> ().enabled = false;

Why isn’t this working ?

Here is a pic of my setup:

“The name GraphicRaycaster does not exist in the current context”

are you

using UnityEngine.UI;