Changing Camera Background Color

I know there is quite a few questions on this but none of them are helping, I have the script and it just doesn’t work.

using UnityEngine;
using System.Collections;

public class CameraBackgroundTest : MonoBehaviour
{
	public Color red = Color.red;
	Camera cm;

	void Start()
	{
		cm = GetComponent<Camera>();
	}

	void Update()
	{
		if (Input.GetKeyUp ("Jump")) 
		{
			cm.backgroundColor = red;
		}
	}
}

Theres the code. One other thing, the inspector says:

The referenced script on this Behaviour (Game Object ‘Main Camera’) is missing!

Idk what this means.

Hello,

Make sure your script is attached to the Main Camera. Also your camera property clear flag should be solid color

Hope it helps!!