Magic Trackpad not clicking on Mac despite Bluetooth connection

Magic Trackpad connects, moves pointer, but won't click. Solved, some combination of these steps:

• Bluetooth settings... Trackpad... Forget this device,
• Turn bluetooth off, then back on
• Turn trackpad off, then back on
• Reconnect trackpad

[Re-Titled by Moderator]

Original Title: Magic Trackpad won't Click