When you are attaching an old document on the Financial Details (FI) screen to an exchange, make sure you first type the document number of the transaction to be exchanged (old document) in the Add 13-character Old Document # textbox. Then click on the Add button instead of just pressing Enter.
Once you click on Add, the Exchange Support screen displays. Add the ESAC code, and if necessary, any Admin/Penalty and Comm Admin/Penalty.
Click the Add button again. The transaction is not complete until you click the Add button the second time and the Exchange Support screen is redisplayed. This will let you know the old document is connected to the exchange.