Please check the points below.
Is the battery set?
Is the type of battery you use R2032?
Isn't the battery you use run down?
Is your Bluetooth setting of your smart phone turned on?
(If iPhone / iPad) Is silent mode off?
If the above list doesn't solve your problem, please try the ways below/
Restart your smart phone.
Restart your Moff Band once or twice.
Restart your Moff app.
Uninstall your Moff app and re-install it again.
If the problem persists, please email to email@example.com and let us know your current situation.