First , please check the cable to see if it is loose. If it is ok, then please check your camera
resolution to see if it match your DVR as follows:
Go to DVR's Main Menu - Setup - Record - Record Bitrate.
If you DVR is 960H , then the camera should be 960H too.
If it still not work, then we suggest you to try upgrade the DVR.
You can refer to the link below to upgrade your DVR:
For example, you need to upgrade the DVR.
Please find the correct upgrade file from the below link: