Inconsistent Port Discovery

I'm trying to get my head wrapped around the discovery of ports.  I've tried a number of different discovery options and I can't get consistent results identifying ports that are being listened to on a server.  For example:

My UCMDB environment is 10.21 CUP 1 CP 15.  My Exchange server has a number of TCP ports being listened to by various processes.  Some of those ports are not defined in the portNumberToPortName.xml file (all defined ports are selected for discovery), so I don't expect to get ipServiceEndpoint CIs created for those, but some of the standard ones, like 25 for SMTP and 80 for HTTP are being listened to by processes on the server and are defined in that file.  I get no ipServiceEndpoint CIs for them.  On the other hand, I have ipServiceEndpoint CIs getting created for ports that aren't even listed in the XML file.

HP documentation is very sparse on setting up discovery for ports, and I don't see very many questions on the subject on this board.  This leads me to believe I'm either missing something fundamental to porperly configure this or that very few people are using UCMDB to discover open ports.

So, am I missing something obvious?