We have a Digital Yacht AIS transponder and a Standard Horizon Matrix GX 2000 VHF. It has all worked perfectly for a few years, we picked up targets through WiFi on a tablet but also saw them through a hard wire on the VHF display. Two weeks ago we noticed the VHF display was not showing all targets in range and then started showing targets that didn't exist. Then a few days later it stopped showing any targets although it still shows our GPS position. The targets still show on the tablet through the WiFi. The wiring seems OK as far as we can tell. As you might expect each company is blaming the other company's instrument. Has any one else had this problem or have any suggestions. We find the VHF display useful as an early warning system, particularly overnight as it is in the cockpit.