触发器无效且未通过重新验证

创建触发器有问题

create table orders(
orders_id number(4) not null primary key,
orders_mem_id number(4),
orders_goods_id number(4),
orders_pay varchar2(50),
orders_carry varchar2(50),
orders_num number(4),
orders_date date,
orders_status varchar2(20)
)
CREATE SEQUENCE orders_id_sequence 
INCREMENT BY 1
START WITH 1
NOMAXVALUE
NOCYCLE
NOCACHE
order;
create or replace trigger tri_insert_orders
before insert on orders
for each row 
begin
select orders_id_sequence.nextval into :new.orders_id from dual;
end;