Creating a reservation after a Misc Receipt

We are trying to automate a process of doing an Account Alias Receipt of a serialized item and then creating a reservation for that same item against a sales order.

The issue we are having is getting the serial to be available immediately after the receipt transaction has occurred.

We are performing the receipt by populating the "mtl_transactions_interface" and "mtl_serial_numbers_interface" tables and then we call "inv_txn_manager_pub.process_transactions" to push it through.  After that, we call "inv_reservation_pub.create_reservation" in order to reserve it to the sales order but we get an "Invalid Serial Number".