Hi, I suggest you email our service tech in the Boca Raton office. 51DiveWar@us.mares.com. His name is Brad and has alot of experience with the computer. I am assuming you have it pressurized? It could also be that the battery in the transmitter is low. Again I would try to correspond with Brad first. Please give him as much detail as possible, ie: serial number on the transmitter and computer. I'm sure he'll get you squared away.