No image from computer onto whiteboard. Projector works. Mouse is on the whiteboard. Sound is good. It shows my wallpaper but not anything that is on the screen. No icons, no messages, no anything. Computer is an old IBM Thinkpad
William, sounds as though your computer image is set to Extended. You need it on Duplicate. You should be able to switch among those settings by holding down the FN key and pressing the appropriate function key on top — the one for the display, usually around F4 or F5 — until you land on Duplicate. Then you’ll see the same image through the projector as on your display.