Hooking Up To A Slider

I'm trying to make slider "Throttle" set a value. There is no gameObject value, rather I'm trying to change a value in a script. I've attached my ThrottleControl script to the "On Value Changed" component in the inspector. The script includes a public function with a float parameter.

I've watched the "Slider" tutorial and it says that this should expose that function so that I can select it in the inspector. It doesn't. Any ideas what newbie mistake I'm making here?

using UnityEngine;
using...

Hooking Up To A Slider