Dotty support
Write to hi@tarekalward.com and you'll hear back from a person. If you bought a key, replying to its email works too.
The screen isn't found
Only one app can talk to a screen at a time, so close the iPixel Color app, and Dotty on your other devices. Then check the screen is on and within a few metres. A screen Dotty can use shows up as LED_BLE_ followed by eight letters and numbers. If nothing like that appears, it may be a different kind of screen.
The screen shows its LED picture
A send was cut off partway. Open Dotty and it sends the picture again.
A key won't activate
A key works on up to three Macs and iPhones in all. Settings, License shows which ones, and you can move it from one to another there.
Which screens work
Generic 32x32 LED screens made in China for the iPixel Color app. They're sold under many brand names, usually as a bare panel on a suction-cup arm with a USB cable. Frames that use the iDotMatrix or Divoom apps won't work, and nor will other sizes. The home page has a checklist and listings that match.
Dotty by Tarek Alward