Do you mean the 'Update EPG' button? Probably the easiest thing to do is check you get listings in the TV Guide after it completes. If not, zip and attach the logs and post them, and I'll check for any errors when it was updating the guide.
If you're using xmltv EPG source, the most common reason for not having listings is problems with whatever utility is creating the .xml files. (like the website it's downloading from has changed etc)
If you've got a C:\Users\Public\NPVR\Scripts\UpdateEPG.bat file, then the application will definitely be running it each times it does an epg update.
One thing to remember though when creating an UpdateEPG.bat - when it's run by the recording service overnight, the default path is something like c:\windows\system32, not the C:\Users\Public\NPVR\Scripts directory, so the batch file will probably need to explicitly change to the directory it expects to be running from.