There could be several reasons for this, check the following: Check the batteries have been installed correctly and the positive ends are pointing in the correct direction. Remove and reinstall the batteries (see, “How do I install/remove batteries?”). Check that your smart phone or tablet has its Bluetooth turned on. Force quit the app and relaunch it. If your smart phone or tablet's Bluetooth is turned on, turn it off and back on. If you use any other devices with the scale, turn their Bluetooth off (you can turn it back on once the scale has connected to your chosen device). Try restarting your smart phone or tablet. Try new batteries. If the problem persists, please contact Customer Support [LINK] for assistance.