Inventory image not showing up

I have made a inventory system but when i open the inventory, i just see the slots, not the items. What do i do? Here are the scripts:

Item:

 using UnityEngine;
 using System.Collections;
 
 [System.Serializable]
 public class Item {
     public string itemName;
     public int itemID;
     public string itemDesc;
     public Texture2D itemIcon;
     public int attackDMG;
     public int attackSpeed;
     public int def;
     public int manaUse;
     public ItemType itemType;
 
     public enum ItemType {
         MeleeWeapon,
         Consumable,
         Block,
         Crafting,
         Gun,
         Spell,
         Helmet,
         Chestplate,
         Leggins,
         Boots
     } 
 
     public Item(string name, int id, string desc, int DMG, int speed, int manaUseage, ItemType type) {
         itemName = name;
         itemID = id;
         itemDesc = desc;
         itemIcon = Resources.Load<Texture2D>("Item Icons/ " + name);
         attackDMG = DMG;
         attackSpeed = speed;
         manaUse = manaUseage;
     }
     public Item(){
 
     }
 
 }

ItemDatabase:

 using UnityEngine;
 using System.Collections;
 using System.Collections.Generic;
 
 public class ItemDatabase : MonoBehaviour {
     public List<Item> items = new List<Item>();
     
 }

And finally, Inventory:

 using UnityEngine;
 using System.Collections;
 using System.Collections.Generic;
 
 public class Inventory : MonoBehaviour {
     public int slotsX, slotsY;
     public List<Item> inventory = new List<Item>();
     public List<Item> slots = new List<Item>();
     private ItemDatabase database;
     public bool showInventory = true;
     public GUISkin skin;
 
     // Use this for initialization
     void Start () {
         for (int i = 0; i < (slotsX * slotsY); i++) {
             slots.Add (new Item());
             inventory.Add (new Item());
         }
 
         database = GameObject.FindGameObjectWithTag("Item Database").GetComponent<ItemDatabase>();
         AddItem (0);
         print (InventoryContains(0));
         print (InventoryContains(1));
     }
 
     void Update(){
         if (Input.GetKeyDown(KeyCode.I)){
             showInventory = !showInventory;
         }
 
     }
 
     void OnGUI(){
         for (int i = 0; i < inventory.Count; i++) 
         {
             GUI.skin = skin;
         }
         if(showInventory){
             DrawInventory();    
         
         }
     }
     void DrawInventory() {
         int i = 0;
         for (int x = 0; x < slotsX; x++){
             for (int y = 0; y < slotsY; y++){
                 Rect slotsRect = new Rect(x * 60, y * 60, 50, 50);
                 GUI.Box(slotsRect, "" , skin.GetStyle("slot"));
                 slots[i] = inventory[i];
                 if (slots[i].itemIcon != null) {
                     GUI.DrawTexture (slotsRect, inventory[i].itemIcon);
                 }
                 i++;
             }
         }
     }
     void AddItem(int id) {
         for (int i = 0; i < inventory.Count; i++){
             if (inventory[i].itemName == null){
                 for (int j = 0; j < database.items.Count; j++){
                     if (database.items[j].itemID == id){
                         inventory[i] = database.items[j];
                     }
                 }
 
                 break;
             }
         }
     
     
     }
 
     bool InventoryContains (int id){
         bool result = false;
         for (int i = 0; i < inventory.Count; i++){
             result = inventory[i].itemID == id;
             if (result) {
                 break;
             }
         }
         return result;
     }
 
 }

Images:

The hierarchy:

The item database:

The inventory object:

What appears:

What SHOULD appear (I edited the image):

Edit: Now, when i open the inventory i get a single inventory square and get spammed with an error saying something on the lines of "Argument is out of range"

Edit Edit: I don't get the error(s) anymore, now the image just doesn't show up. I've tried adding the item by index creating a test item. So it seems that it's something that's wrong with the DrawInv function.