PO number not flowing to SRM

Hi,

We have a classic scenario implemented and we are using standard SRM Interfaces in SAP PI to enable data flow between SRM-ECC.

Namespace: http://sap.com/xi/APPL/Global2

Interface: PurchaseOrderERPConfirmation_Out

Below is the XML extracted from PI System when the PO Number is updated in SRM

Image may be NSFW.
Clik here to view.

Below is the XML extracted from PI System when the PO Number is not updated in SRM and

<CompletenessAndValidationStatusCode>3</CompletenessAndValidationStatusCode> is returned in XML

Image may be NSFW.
Clik here to view.

Can any one suggest what validation error it could be, any suggestion would be appreciated.

Regards,