Can't update value in mySQL database - mysql

Question

So I'm trying to make a simple scheme of order-> payment-> shipping. Here is the structure of the main tables:
cust_order (order_id, customer_id, catalog_id, items_ordered, order_date, payment_status(Paid/Unpaid), shipping_status (Preparing/Shipped))
payment (payment_id, order_id, pay_bank, pay_accnum, pay_date)
shipping (shipping_id, order_id, shipping_date)
And the plot is:
An order was made. The default value of payment_status would be Unpaid and shipping_status = Preparing
(Trigger 1) If an order was made, then a row will be inserted on payment table, with the value of pay_bank, pay_accnum, pay_date is NULL
Assume that the customer has paid, the value of pay_bank, pay_accnum, pay_date has been filled. Then (Trigger 2), the payment_status on the order table will be changed to 'Paid'
(Trigger 3) if the payment_status on the order table is changed to 'Paid', then a row will be inserted on shipping table (so the shipping admin can see the order that need to be sent) with the shipping_date value is NULL
Assume that the shipping admin has send the product, he edited the value of shipping_date, so it's no longer NULL. Then (Trigger 4), the shipping_status in order table is changed to 'Shipped'
I've created all the 4 triggers. Here is the code:
Trigger 1
create trigger order_to_payment
after insert on cust_order
for each row
begin
insert into payment (order_id,catalog_id)
values (new.order_id, new.catalog_id);
end;
//
Trigger 2
create trigger verifPay
after update on payment
for each row
begin
if new.pay_bank is NOT NULL and new.pay_accnum is NOT NULL and new.pay_date is NOT NULL then
update cust_order
set payment_status = 'Paid'
where order_id=new.order_id;
end if;
end;//
Trigger 3
create trigger paid_to_shipping
after update on cust_order
for each row
begin
if new.payment_status = 'Paid' then
insert into shipping(order_id,customer_id)
values (new.order_id, new.customer_id);
end if;
end;
//
Trigger 4
create trigger ChangeShippedStatus
after update on shipping
for each row
begin
if new.shipping_date is NOT NULL then
update cust_order
set shipping_status='Shipped'
where order_id=new.order_id;
end if;
end;//
And here I found a trouble when I'm trying to edit the pay_date value on the shipping table, it says #1442 - Can't update table 'shipping' in stored function/trigger because it is already used by statement which invoked this stored function/trigger
I've made a similar scheme before and it worked, so I'm trying to figure out where the problem is in this case