Shipping Bill under Advance License - Customs - Exim - SEZ

Dear All, We are DTA Unit and we have obtained Advance Authorization to purchase raw materials from the SEZ Unit. At the time of Import Raw Materials from the SEZ Unit against Advance Authorization, We do not pay IGST. After receipt of raw materials, we have manufacture finished goods and export to foreign country. At the time of filling of shipping bill under the Advance License, we have file the shipping bill under IGST Refund and not LUT. Custom officer reject the shipping bill and inform us that shipping bill has to be file under the LUT and not IGST Refund as at the time of purchase raw materials from the SEZ Unit, you do not pay the IGST. is this stand of custom officer is correct ? Kindly inform with support of any circular, notification etc.. Regards, Ritesh Dave