Solved event.setCancelled(true); not cancelling event

sometimes, when Im clicking the inventory with a stack of sand or something, the stack of sand will get placed into the inventory, and I'm not sure why.
Am I not canceling the event properly?

Code:

    @EventHandler
    public void onInventoryClick(InventoryClickEvent event) {
       
        int cooldowntimer = 30; //(30 minutes)
       
        Player player = (Player) event.getWhoClicked();
        if (event.getClickedInventory() != null) {
            if (event.getClickedInventory().getTitle().equals(ChatColor.GREEN.toString() + ChatColor.BOLD.toString() + "The Grand Minechange")) {
                if (player.getItemOnCursor().getType() == Material.AIR) {
                    System.out.println("tas");
                    ItemStack clickstack = event.getCurrentItem();
                    if (clickstack.getType() != Material.AIR) {
                        System.out.println(clickstack.getType());
                        if (clickstack.getItemMeta().hasDisplayName()) {
                            if (clickstack.getItemMeta().getDisplayName().equals(ChatColor.YELLOW.toString() + ChatColor.BOLD.toString() + "Create Request")) {
                                long timeleft = System.currentTimeMillis() - main.getCooldown(player.getUniqueId());
                                if (timeleft > cooldowntimer * 60000) {
                                    Inventory crinv = createrequest.createInventory();
                                    event.setCancelled(true);
                                    player.openInventory(crinv);
                                } else {
                                    player.sendMessage(main.prefix + ChatColor.RED + "You must wait before making another request!\nTime left:" + Integer.toString((int)(timeleft / 1000)) + 's');
                                }
                            }
                        }
                    }
                }
                event.setCancelled(true);
            }
        }
    }
   
}

turns out I wasnt accounting for InventoryDragEvent

EDIT by Moderator: merged posts, please use the edit button instead of double posting.