I've bought a HDMI to VGA adapter (no external power source) so I can use my mid-2015 Macbook Pro with the old projector I have in class. Thing is, as soon as I connect it to the HDMI port (even without connecting the projector to the adapter), the mouse cursor starts to lag and drag, and the screen continuously goes off and on, off and on. When I connect the projector to the VGA port of the adapter, the problem keeps happening, and no image is shown by the projector.
The adapter is an off-branded one, but I tested it on my Windows notebook and it worked fine. Back in the Mac, I tried to take a look at the System Preferences -> Displays, and the adapter/projector doesn't show there.
When I disconnect the adapter, the screens goes back to normal, as does the mouse cursor.
What could be happening?
Macbook Pro Retina 13" - Mid 2015 - El Capitain