This article will cover how to troubleshoot the TNSListener for Oracle, this will include checking the status as well as recreating the Listener.
This would apply to any environment where Oracle and Enforce are having problems communicating due to the TNSListener.
1. Ensure your connection information is specified correctly on the Enforce Server
2. Check the status of the TNSListener
3. If you have run through the above steps, and the Listener is still not running, go ahead and simply recreate the TNSListener.