Update Record After Insert

Using trigger
want to update a field being inserted from another record in the same table.

the record being inserted I want to pull the bkjrcode from another record where the account = 1040 that also has the same ord# and inv# as the record being inserted.

Here is what I've tried with no luck.

create trigger [updategbkmut] on [dbo].[gbkmut]
after insert
as

update g1
set g1.bkjrcode = g2.bkjrcode
from gbkmut g1
inner join inserted i
on i.ord_no = g1.ord_no and i.inv_no = g1.inv_no
inner join gbkmut g2
on i.ord_no = g2.ord_no and i.inv_no = g2.inv_no
where i.freefield3 = 'Rebate' and g1.account = '1040'