I can only make a couple of suggestions, based on real world experience with VOR navigation.
1. Make sure the station you are tuning is in fact a VOR, VORTAC, or VOR/DME facility.
2. Be sure the frequency you input to the nav radio is accurate and correct for the desired station.
3. Once the frequency is verified corect, turn up the nav radio volume and listen to the morse code identifier...it should match what you see on the chart. If it doesn't match, your frequency is incorrect.
4. Turn the OBS to match your current heading, the needle should center. Then turn the OBS to the desired radial and navigate to or from the station.
Hope this might shed some light!