Share screen of the phone during desktop meeting

Hi,

during meeting on desktop zoom, I trained on a software and its app. Sharing screen on the computer was just fine.

I joined the zoom through my phone too and wanted to share screen of the phone, clicked share, clicked screen.

Phone has green sharing line

Desktop screen says the phone has started screen sharing, but the screen is black.

i have allowed zoom within the settings, but now I don't know.

The phone took over the running the meeting too, that didn't help. 

this is Samsung galaxy 21.

thank you very much for any help