To activate the Transparent Database Engine:
In ISN, go to Settings --> Office Settings --> Payment Options. Scroll down to eProcessingNetwork and activate this setting:
Be sure to hit "Save" at the bottom of the page once you activate it.
Next, we need to make sure your EPN is setup to work under the TDBE:
Login to your eProcessingNetwork account here: https://www.eprocessingnetwork.com/msclogin.html
Next, navigate using the below screenshots:
Once this is done, your ISN will process EPN transactions under EPN's native engine TDBE, which has better support for refund and void transactions.