ASN does not net against PO in ASCP plan

Hello!

I am loading Advanced Shipment Notices (ASN) from supplier directly into planning instance using the "Load Transaction Data using Self Service Loads" concurrent program.The ASN is referencing the PO number that it is shipped against. However, when I run the ASCP plan, the ASN is seen as "In Transit" supply on top of the PO quantity. I expected that the plan should not consider ASN as additional supply, but should be netted off against the PO quantity. Appreciate any pointers on how to make this work correctly.

Cheers!