2002 RX300, no Disk dected?

6 months ago my sat nav quit working while on a out of town trip. When I restarted the car the NO DISK DETECTED popped up on the screen. I called Lexus about it and was told that it was timed out and that I needed a new disk. This week I bought a new disk from lexus and installed it. I still get NO DISK DETECTED. Thanks, John