Linda,
A few things come to mind: from what I can see, there aren't a log of radio systems in your area so I don't suspect you have a lot of channels programmed into your scanner. Are you certain that the frequencies that you have programmed into the channels aren't locked out? Though I don't have your model of scanner, I've had some that will lock out channels. They're programmed in to the scanner but the scanner ignores them during scanning. If you manually scroll through the channels, do you see the word "lockout or L/O"?
Another thought (I'm assuming your area to be a rural one) is that you may not be close enough to pick up radio traffic. Maybe a trip to downtown may net you better results. (It usually legal to go mobile with a scanner but it wouldn't hurt to check your state and local laws) If all is good to go, just be discreet, as some people get "weirded out" about such activities. If going mobile with your scanner is too dificult, an outdoor antenna may be of benefit.
Lastly, from what I see you're correct about there not being any trunked systems. This should make programming a bit easier. One last thing to try: Instead of scanning, manually park your scanner on one frequency, say sheriff or fire dispatch, for a few hours and see if you get any traffic.
