Error of screen sharing

I got an error when I shared the screen, people couldn’t see what I was sharing, I just saw the screen was dark. I don’t know what problem I have. please help me. Thanks!

windows or Mac?
if windows, try to change capture method in preferences, if won’t help check the antivirus/internet security
if Mac - this most likely to be permission problem that controls whether or not OS allows us to capture the screen

Can you give me detailed instructions? I’m new so I don’t know much yet. please !!!