functional ackonwledge ment positive status 16

HI

we use OPUS as warehouse mgt and SAP ECC 6.0 for ERP , we recieve ASN's Via IDOC to AS400, we did't seem some ASN's on OPUS which we can see on SAP i checked the DESADV idoc status message showing Status 16, so is something to do with AS400 or SAP if IDOC sent to external system means we need to fix something on AS400(ie port ) or this is related to XI

Thank you

ash