Because of the many ways one can start JBossAS (using the standard run.bat, writing your own custom script to run it, running it as a service as you have done here via some custom service.bat, et. al.), it would be impractical to be able to code up the agent (more specifically the JBoss agent plugin) to be able to auto-detect JBossAS that was run in all these different ways. Today, it tries to detect it by peering in the operating system's process table and looks for a certain signature of the process that would match a typical JBossAS server (i.e. look for "java" or "java.exe" process that is running a "org.jboss.Main" class - see the JBoss plugin descriptor's "process-scan" element for the patterns it looks for).
If for some reason your JBossAS process cannot be auto-discovered, all is not lost. You can "manually add" your JBossAS Server resource into inventory - effectively helping the agent find your JBossAS Server. From the GUI, navigate to the platform resource (which must be in inventory already) and somewhere (depending on the version you are using - usually its in the Inventory subtab) you can select the "manually add" option (in our latest version of the GUI its called "Import") and tell it all the information the agent needs to find and manage your JBossAS server - this means filling in all the connection settings such as the JNP URL. See the documentation for more information on how to manually add a resource into your inventory.