Sender AS2 to SAP PO; 403 forbidden error

Hello Experts,

I am using the AS2 adapter from the B2B Addon.

I am stuck in the scenario Sender AS2 -> SAP PO; with the 403 forbidden error.

Few queries;

1. Is virtual receiver mandatory ?

2. Is is mandatory to have party for sender and receiver. Currently I am having only Sender ( Party + Comm. Component ) and Receiver ( Comm. Component ( Partner Type = LS )).

Can you help please.

Thanks

Saurabh