As an exporter, we Fax an American businessman to export agricultural products. Beside the necessary items stated in the offer, the clause "Packing in Sound-bags" is also added in. During the validity of the offer, t h e American businessman replies "Refer to your telex first accepted. Packing in new bags". When we receive the above reply, we are ready for shipment. However, t he international market price for the agricultural products tumbled these days . The American businessman replies that the contract was not established because we did not confirm when they changed the packing condition in the reply . We insist that the contract has been established. Should this contract be regarded as established or not according to CISG? Why?