I also have an I/O Linc for a garage sensor. I tried to add the device to my ISY 99i firmware 3.3.10 and receive the same Cannot Determine Insteon Engine error message.
Factory reset has been performed and I still receive this error.
Here is the Diagnostic Event Viewer Level 3 output (pretty limited):
Mon 12/15/2014 10:18:46 PM : [1F A 2D ] Added to list of devices to link to ISY Mon 12/15/2014 10:19:07 PM : [1F A 2D 0 ] Failed to add device
I have over 30 Insteon devices in my house and this is the only one that the ISY 99i cannot add/see in the Admin Console.
Any ideas?
Thanks,
DeLo