Start by making sure your favorite list is actively being scanned. In Sentinel, ensure Download and Monitor are both ON. If Download is off, the list will not be copied to the scanner, and there is no way to scan it.
Make sure your Service Types are turned on.
Make sure your location is set correctly. Manually entering your GPS coordinates is better than entering a ZIP code, because you may live miles away from the geographic center of the zip code area.
Turn on the full database and see if you get any traffic scanning that way. If you do, then you probably screwed up something in your favorite lists. The most common error is deleting the broadcast sites for a trunked system, which makes it impossible for the scanner to hear the system.