Purchase Order document is failing in CIG due to Source Content Schema Validation Error

Hi DSN Experts,

Need your expertise comments on the below PO failing in CIG.

My Client is in the process of implementing DSN for SAP S/4 HANA 1909 (On Prem).

I am in the process of testing the Purchase Order document (Order Request) posted in S/4 HANA 1909 from the back end system and this has failed in CIG. I copied the failed PO payload from CIG and pasted into the CIG Document Validator > and when I click on "TEST" key I see failed Status as Source Content Schema Validation and Target Schema Validation error (Status Indicator as X) as shown in the below images.

When I see on Source Content Schema Validator summary key I see the below error

Source Content Schema not available for Document : AddOn - Order - ARBCI10010

Similarly, Err in Target Schema Validation shows err as below (Screen Shot)

We have implemented the Customer Exits / BAdi's related to the Purchase Order as well.

By looking at the err at "Line# 106 PostalAddress" I double checked all the Postal address data from the backend Supplier Master data / Contact Person Address maintained in Business Partner as Relationship as well. All seems to be ok.

I didn't see IDOC segment "E1ARBCIG_PARTNER_INFO" appearing in Outbound PO IDOC

We are using AddOn Info1 -ARBCI100 and AddOn Info2: ARBCI20008

I see the below AddOn had been installed.

Appreciate Expertise comments.

Thanks in advance

Regards,

Srinivas