Keynote connection to a projecor
I have started having problems connecting my Mac to a projector. When I plug in the adapter, the computer connects immediately, but then no image appears on the screen. If I connect it directly with HDMI to a TV, it works, but from the computer to a projector, it stops working. I've only had this problem for the past six months, and I've been on stage for over 20 years.
We tested five different Mac computers to connect. 4 did not work. Only 1 computer with an old operating system worked.
Can someone help me?
MacBook Air 13″, macOS 10.13