A1. Turn your systems Bluetooth off/on.

A2. Remove and re-pair the mouse to your Mac:

Go into your system preferences and open your Bluetooth settings.
Locate and remove the Macally mouse shown in the Bluetooth window.
Once the mouse has been successfully removed, press and hold the pairing button located on the underside of your mouse for 3-4 seconds to put it into pairing mode.
Note: BTDynaMouseusers will need to press and hold the “Scroll Wheel and Right Click Button” at the same time for 3-4 seconds.

At this point you should now be able to re-connect the mouse that shows up in the Bluetooth window.

A3. Reset the Mac’s Bluetooth Module:

If removing and re-pairing the device doesn’t work, you may need to reset the Macs Bluetooth module. Keep in mind that this is going to disconnect every Bluetooth device on the Mac, so if you only have a Bluetooth keyboard and mouse you’re going to temporarily lose the ability to use those devices as the Bluetooth hardware module is reset. 

1. From the Mac desktop, hold down the “Shift+Option” keys and then click on the Bluetooth menu item to reveal the hidden Debug menu.

2. Select “Reset the Bluetooth module” from the Debug menu list.

3. When finished resetting, go through the process of connecting the Bluetooth device(s) to the Mac as you typically would, everything should now work fine

Important Note: Some USB hubs and adapters are known to cause interference.  If you use such an adapter on your computer please try removing it from your computer and you may find that your Bluetooth device works more smoothly than it did before.