The most extreme problem is seeing nothing at all on the screen. Check all the same things you would look at during the day. Make sure the camera has power, ensure all the connections are secure and that the infra red is illuminating. If that is all in order then stand in front of the camera quite close to it. Infra red needs to bounce off a surface back into the camera. If you just point the camera into space it won't see anything.
If it is a new camera then it could be that the electronics aren't sensitive enough. Don't rely on quoted specs, these are often pure fantasy. How does the camera react as the light fades at the end of the day? A good CCTV camera should deal with low light conditions better than the human eye. It should still show what looks like a day time image when the naked eye thinks its getting quite dark.
If you see a white screen at night then the most common problem is infra red light reflecting back into the camera lens. The wider the angle of view the more chance there is of this happening. On vandal dome cameras check to make sure any sealing rings which fit between the lens and the inside of the clear plastic cover are securely in place.
Whilst you can't see the infra red light to the camera it is extremely bright and any surface close to the front of the camera can reflect the light back into the lens. Even if the surface is out of screen shot it can still reflect the IR. If you can't move the camera try zooming it in more so you narrow the field of view.
Light pollution from other sources can also cause white areas to appear on the screen. Vandal dome cameras are particularly prone to corruption from external light sources.
Well it will do. The glass is a reflective surface and it's right in front of the camera. The infra red will bounce off the glass straight into the lens causing the camera to dazzle it's self.
When the infra red switches on the camera draws more current. If your power supply is marginal or not powerful enough this extra current draw could cause problems. Also make sure you have not exceeded the recommended cable run length and that the cable is substantial enough. Voltage drops along the length of the cable and the thinner the cross sectional area of the cable the more this happens.
Check the camera for spiders webs. During the day you don't notice spider webs. The camera focuses beyond the web and it appears invisible. At night the infra red bounces off the web and it shows very clearly. We do sell a spider spray to help reduce this problem.
This is similar to the spiders web problem but instead of a web the light is reflecting off dust or particles in the air. This is particularly noticeable in fog where the water droplets suspended in the air reflect the infra red. Warm currents in the air can cause particles to rise as well as fall.
This isn't an exhaustive list of problems encountered at night but it covers the most common ones.