Why I can not see the camera image on the connected monitor?

At first, please check the camera’s type, such as NTSC or PAT and then adjust the correct system type on the rear panel of DVR before turning the power on. After that, the display can show up normally.
Please be noted, the DVR-462 and DVR-1672 has NTSC/PAL switch on the rear panel and the DVR-872 can detect automatically.