3189079 - Error: "Managed Gateway for Spend&Network is unable to determine incoming document type/standard" when sending payment remittance from SAP ERP to Managed Gateway for Spend&Network

Payment remittance document from SAP ERP to SAP Business Network fails in Managed Gateway for Spend&Network transaction tracker with the following error:

ANXXXXXXXXXXXManaged Gateway for Spend&Network is unable to determine incoming document type/standard. Suggested Action : Please verify the following in the incoming request are valid and pre-provided to Managed Gateway for Spend&Network. Namespace -> namespace provided in the request is a valid and preapproved to Managed Gateway for Spend&Network to have integration established. Document Structure -> the Incoming request to Managed Gateway for Spend&Network is of valid structure. For further assistance, please contact Managed Gateway for Spend&Network Support with Error Code: CIG-PLT-05663

Also, the first segment has the following incorrect structure in the preprocess payload:

<ARBCIG_REMADV xmlns="urn:sap-com:document:sap:idoc:soap:messages">

KBA , BNS-ARI-CI-AN , Managed Gateway for Business Network , Problem