ISY 994 cannot communicate with garage door sensor (74551)

[Captain]

I have installed the I/O Linc garage door control and have linked it to my ISY but the ISY cannot communicate with the sensor on the door. I have a green light on the sensor status at the I/O. I tried a FilterLinc out of curiosity but no luck. Next step?

[LeeG]

Move the I/O Linc to the PLM plug point to confirm it is working. Simply connect a short piece of wire to short GND and Sensor to see if I/O Linc is reporting state change. If it does not work at the PLM plug point it could be a link record problem in either the PLM or the I/O Linc, or a defective I/O Linc. If it works at the PLM plug point then work on the Insteon network.