Hi everyone, need to BI. I have BI running with 9 cameras around the house.

I have 4 of them with continuous recording and the other only when triggered.

Is there a way to say go back and see if my Mail Carrier dropped of a package say 45 minutes ago.. Every time I try to view something in the history all the cameras on the screen are black. what im I doing wrong? If I have a camera on continuous recording, and what to setup a trigger, is cloning the camera the best option?
Thank you.