Adding to Config Help

When I do this command, I want to add kills to a player's killcount. I need just need a little help.

Code:

           
            if (cmd.getName().equalsIgnoreCase("add"))
               
            {
               
                if (args.length == 1)
               
                {
               
                    if (sender.hasPermission("server.add"))
               
                      {
                       
                Player player = (Player) sender;
                String name = player.getName();
               
                int killCount = getConfig().getInt(name + ".kills") + 5;
                getConfig().set(name + ".kills", killCount);
               
                sender.sendMessage(ChatColor.GREEN + "You have added " + ChatColor.GOLD + "5 " + ChatColor.GREEN + "coins to your total!");
                sender.sendMessage(ChatColor.DARK_GRAY + "> " + ChatColor.GRAY + "You have " + "" + this.getConfig().getInt("kills") + "" + " kills!");
               
                ItemStack fivesf = new ItemStack(Material.DOUBLE_PLANT, 5);
                ItemMeta sm = fivesf.getItemMeta();
                sm.setDisplayName(ChatColor.GOLD + "Coins");               
                fivesf.setItemMeta(sm);
               
                player.getInventory().addItem(fivesf);
               
                      }
                   
                    else
                       
                      {
                       
                        sender.sendMessage(ChatColor.RED + "You cannot execute this command.");
                       
                      }
                   
                }
               
                else
                   
                {
                       
                sender.sendMessage(ChatColor.RED + "Usage /kills");
                       
                }
               
                return true;
               
            }
            

 

You're not saving the config