Trouble accessing a variable in another script, C#

I've been searching Unity answers for how to do this, and it's covered a lot. But when I try to do it, I still have trouble getting one script to recognize the existence of another:

I have a script called FlyingActivator on an object called Player. In it there is a public boolean variable called EnableFlying.

I need to set the EnableFlying variable to !EnableFlying from another script ("WaitToFly"). This is a stripped down version of what I'm using to do it:

     using UnityEngine;
     using System.Collections;
     
         public class WaitToFly : MonoBehaviour
         {
             void Start()
             {
              GameObject g = GameObject.Find("Player");
              FlyingActivator e = g.GetComponent<FlyingActivator>();
              e.EnableFlying = !EnableFlying;
             }
         }

Except I'm getting this error:

The type or namespace name `FlyingActivator' could not be found. Are you missing a using directive or an assembly reference.