help needed on and off switch for invis

Code (CSharp):

1. using System.Collections;
2. using System.Collections.Generic;
3. using UnityEngine;
4.  
5. public class box : MonoBehaviour
6. { public MeshRenderer sr;
7.     private void OnTriggerEnter2D(Collider2D collision)
8.     {
9.         if (collision.transform.gameObject.name == "Diamond") { sr.enabled = false; }
10.         if (collision.transform.gameObject.name == "Diamond" && sr.enabled = false) { sr.enabled = true; }
11.     }
12.  
13.  
14. }
15.  

im trying to make a on and off invis switch but its giving me this error

CS0131 C# The left-hand side of an assignment must be a variable, property or indexer

and i dont know what it means or how to fix it

 

Line 10, single equal sign in "&& sr.enabled = false" causes the error, should be "=="
Easier to just say !sr.enabled than checking if it's equal to false.

 

thanks hopes it works