How to develop XML for Database using ESI
A device that does not even discover is more of a collection issue than an XML issue.
Do you have other log types coming from the same IP Address? Meaning aside from your custom application, have you already discovered the Operating System orthe Database system itself? If so, have you activated "multi-device"?
If you are looking to pull logs from a database system (or an application that stores logs in a database) then you need to define your query in the Universal Device Collection section of Overview > System Configuration > Services (and also in the Device Services section for ODBC.) If you haven't done that then there is no way enVision would every see the logs.
Now, if you are collecting from something that is already supported, then make sure you've followed the configuration guide.