video on participant’s computer not showing in zoom meeting

Participant can’t get her video to work in our meeting. The video icon on bottom left in the her meeting screen showed it was on but in the meeting she was represented with a schematic icon of a camera with a slash through it. How does she get her camera to work? She has an HP computer and the camera light is on. I’m running the meeting on my Apple MacBook and have the latest zoom workbook app.