I assume you have not chosen "auto-ISO". In A mode what you chose is the aperture. If you have fixed the ISO, then the camera will choose a shutter speed to ensure the correct exposure. In low light, this could result in a very low shutter speed - which is a no-no without a tripod. So you have to bump up aperture, and/or ISO to get the shutter speed within the 1/focal length range.
To see the meter move, go to M mode. Fix all three parameters - ISO, shutter speed, and aperture. Then point it at different lighted or dark area. Alternatively, point the camera at a bright place, press and hold the AE-L button to lock the exposure. Then while holding the AE-L button, now point the camera to a dark place and see the meter move.
For the D7000, I find my copy a little over exposedby default. I would bump the exposure down by -0.7EV by holding downthe +/- button near the shutter release and rotating the thumb dial. Again, the meter will move.