GUI Not coming up?

So, I'm making a basic KitPVP plugin and I just did a tiny bit of it just to test it. Now i'm pretty sure i've done it right, but the GUI doesn't come up when I do the command I specified :/ Any ideas?

Code:

package me.Joel.KITPVP;

import org.bukkit.Bukkit;
import org.bukkit.ChatColor;
import org.bukkit.Material;
import org.bukkit.command.Command;
import org.bukkit.command.CommandSender;
import org.bukkit.entity.Player;
import org.bukkit.event.EventHandler;
import org.bukkit.event.Listener;
import org.bukkit.event.inventory.InventoryClickEvent;
import org.bukkit.inventory.Inventory;
import org.bukkit.inventory.ItemStack;
import org.bukkit.inventory.meta.ItemMeta;
import org.bukkit.plugin.java.JavaPlugin;

public class Main extends JavaPlugin implements Listener{
    public void onEnable(){
     Bukkit.getServer().getPluginManager().registerEvents(this, this);
    }
    
    public boolean onCommand(CommandSender sender, Command cmd, String label,
            String[] args) {
        if(cmd.getName().equalsIgnoreCase("kits")){
           
            Player p = (Player) sender;
           
            if(p.hasPermission("kit.open")){
           
            ItemStack kit = new ItemStack(Material.DIAMOND_SWORD);
               ItemMeta meta = kit.getItemMeta();
               meta.setDisplayName(ChatColor.AQUA + "PVP Kit");
               kit.setItemMeta(meta);
           
   
              
            
               Inventory inv = Bukkit.createInventory(null, 9, "Kits");
               inv.setItem(1, kit);
           
               p.getPlayer().openInventory(inv);
            }
           
           

            }
        return true;

        }
   
    @EventHandler
    public  void onClick(InventoryClickEvent e){
    
       
     Player p = (Player) e.getWhoClicked();
     if(p.hasPermission("kit.pvp")){

    
     if(e.getInventory().getTitle().equals(ChatColor.GREEN + "Kits")){
     
         ItemStack clicked = e.getCurrentItem();
         
         if (clicked.getType() == Material.DIAMOND_SWORD) {
                e.setCancelled(true);
                p.closeInventory();
                p.getInventory().addItem(new ItemStack(Material.DIAMOND_HELMET, 1));
                p.getInventory().addItem(new ItemStack(Material.DIAMOND_SWORD,1));
               
         }
        }
    }
   
    }
}

 

You are using p.getPlayer(), but p is already a player

 

@Bubbatron11 Check your log and think, what's wrong? Normally the problem is around the middle of the error, the 'ERROR' part can be important, I guess. Some stuff that can go wrong with gui's are:
1. Invalid Argument for Inventory Slots,
2. Invalid Player,
3. Invalid input/output,
4. You didn't follow me,
5. ...
Uh, whoops, focus on 1-3. There can also be a small error in your code that isn't noticing to you.
Now forget 5 but keep 4 in mind .