Accessing public variable with the On Click() function list in Inspector

I am trying to detect a UIButton click event in Unity 5.3.31f. I attached a C# script to an empty GameOject, and I am trying to access a bool variable in the script using the On Click() function list in the inspector.

using UnityEngine;
using System.Collections;
public class InputState : MonoBehaviour {
	public bool actionButton;
}

The function is visible in the pool down menu, but the actionButton variable does not appear in the menu. I am not sure what I am doing wrong.66794-screen-shot-2016-03-27-at-51911-pm-2.png

This comes up for me as well once in a while; I’m not sure if class fields can appear at all as targets of event callbacks in the inspector.

What I do is use a public property with only a setter, that refers to the field I declared, like so:

public bool thisIsMyField = true;

public bool myFieldAccessorProperty {
        get {
        // getter is not required, I add it for consistency's sake when accessing
        // the value from other scripts
        return thisIsMyField;
        } 
	set {
		thisIsMyField = value;
	}
}

property setters will appear normally in the OnClick() function list in the inspector.