If I were you, I'd do the following first (or let us know you have done the following, at least steps 1-3, 6):
1. Download Sentinel (and use it for the following)
2. check if you have any firmware need update (Update->Update firmware)
3. Update Sentinel Data Base (Update->Update Master DataBase)
4. Use the Updated database to create a favorite list (FL) (say P25 based trunk system), keep the favorite list small for now to those you believe are nearby (You tube for Sentinel tutorial how to add and then remove Unneeded. Even better, assign it a number
5. Edit the Sentinel default profile ->Scan Selection (check off Monitor full database, but set Monitor & Download FL as on)
5.a Click Service Type tab and make sure the service type as listed in your FL is has check mark (or just flip most of them to on)
6. power up sds200 to mass storage mode and write the FL, AND force update the whole Database to scanner.
eject sds200 storage from your PC as if you would do when ejecting a usb thumb drive B4 power recycle the sds200 scanner.
7. Power on SDS200, see how it goes
The above is to make sure your scanner database is up2date, and by keep your scan list small (into the FL) , in case your area communication is sporadic, you won't miss it that may have missed if using the huge ZIP code based scan list.
Worst case, try scan weather channel or your local FM radio frequency to see if you pickup anything (Download proscan, and you can easy set the frequency at the right side of scanner GUI and click "Tune")