This error generally occurs when there is an issue with your network. A pop-up that says the device disconnected may trigger. If there is a connection problem and you try to reconnect immediately, you will get this message:
Wait about 40 seconds if you have a connection issue before trying to reconnect. You will know the device is connected when all three lights on the tCheck device are Blue.
This issue can also be caused by proximity to other electronics that produce electrical noise such as a laptop charger, power cord, etc.