A very possible scenario is because they did the cheap and lazy "zip code" method (didnt actually program anything for you, just punched in a zip code), and thus, you cannot use ID Search, so if the system is using different talk groups than what's listed, you won't hear a thing.
Try this:
Find the system you are trying to listen to and hold on it by pressing "System" --> press "Chan" (bottom right white button) --> Press "E/Yes" --> Add to Favorites List? -> YES -> It will ask you to name it, name it or just press A, whatever
--> Now, go to "Set scan selection" --> turn OFF the full database, turn ON the favorites list you just made (E/Yes to toggle on/off) --> press "System" --> Once it starts scanning, press "FUNC + YES" to enable ID Search.
Now, you wont have any of the TG IDs/names besides the one you specifically added, but it is a quick and easy way to get a system into a favorites list to get ID Search running.
Personally, I recommend always using ID search, as the DB will never have ALL the TGs, and new ones will pop up, often the most interesting of times, and without ID search, you wont hear them.
If this doesnt work, its possible the LCNs are wrong, in which case you can use the LCN finder - but you will still need to create that favorites list. The best thing about these scanners is the favorites list, they give you control over what you scan. I have 60+ favorites lists, for all different industries, hobbies, etc - doing this enables you to turn on the ones you want to hear, and off the ones you dont, whenever you want, and lets you use ID search instead of ID scan. Make one for whatever you listen to, the more specific, the more control you have (hospitals, airports, public safety, business, federal, statewide, etc)