Please help. Can't add script problem.

I have a really big problem with this script. I did an other one before and it worked. this time is this problem that i can’t add script. Someone please help.
Thank you in advance.

using UnityEngine;
using System.Collections;
using System.Collections.Generic;


public class NewBehaviourScript : MonoBehaviour {
	public List<Item> inventory = new List<Item>();
	private ItemDatabase database;


	// Use this for initialization
	void Start () {
		database = GameObject.FindGameObjectWithTag("Item Database").GetComponent<ItemDatabase>();
		print (database.items [0].itemName);
	}
	
	// Update is called once per frame
	void Update () {
	
	}
}

Try “unity cant add script.” Unity has been around for years, and many people ask this. There are pages and pages of mistakes other people have made, and how they were fixed.

You will find the answer much quicker than a back-and-forth in the comments here.