I was wondering how I can view other people's webcams while chatting on messenger?

I'M ABLE TO HAVE THE OPTION TO VIEW, BUT ALL I HEAR IS A CHIME AND NOTHING ELSE WHEN I CLICK ON THE ICON. OTHERS CAN VIEW MY CAM, BUT I CAN'T VIEW THEIRS. JUST WONDERING IF THERE'S THAT I NEEDD TO DO, OR THEY MAY NEED TO DO TO MAKE THIS WORK. THANKS.