I've been told that this does not necessarily mean that the device is not working but that it may just need to be reprogrammed. (Your body can adjust to the device requiring reprogrammings over time.) You may just need to call the rep who trained you how to work the device and have him come out with his machine and reprogram the device. (Your doctor will not know how to reprogram - only your rep will know.) I believe these devices also need to be recharged from time to time and if you haven't been doing that that could cause problems as well. Good luck!