DSN invoice - invoice not posted due missing vendor code

[S0010900093]

Hi,

We are in S4HANA 1709 environment and was testing invoicing posting from supplier via Ariba Network. The IDoc posted with an error that " customer, vendor [system number] not known". Looked into the Idoc segment E1EDKA1 LF found the the vendor code is not populated.

Had checked the setting in S4 and Ariba and it seemed fine to me.

Any clue what is missing?

Thanks

TS.