Object invisible until mouse hovers button

Unity Engine
1

It did sound very simple to me in the beginning…but somehow i mixed it up too much.
I have a scene with a few buttons and some objects.
I want that when i mouse hover over button1…object1 appears…otherwise the object1 is invisible.

Can anyone help me with that?

Greetings

2 
using UnityEngine;
using System.Collections;

public class ShowTown : MonoBehaviour {

    public GameObject place = null;

    private void OnMouseOver()
    {
        if (place != null && place.gameObject != null) {
            place.gameObject.SetActive(true) = place.gameObject.SetActive(false);
        }
    }
}

This is what i have so far but it doesnt work. I just wanted to drag the object in the inspector when the script works.
But…i did something wrong with the “place.gameObject.SetActive(true/false)”