The DVR needs an internal hard disk drive for recording. Without the hard drive, the system can show live viewing but can record, playback neither.
step 1: Confirm hard drive installed
Newly installed hard drive needs formatting, enter the main menu - advanced -HDD management, click format HDD.
Main Menu—advanced—HDD Management
Go to the main menu--record—video mode
the select channel first.
set up time period
Go to the main menu---record---playback to check recordings.
Here is method