Glad you got a solution; hope it works. I held off reading through an Installation manual until I know what model panel you have.
The "Fail to Communicate" Trouble was my first _guess_, but I didn't want to say it was the trouble without more info. I worked with _most_ of the major brand names for 40+ years, but the Visonic PowerMax wasn't that popular in this part of North America, so although I've worked with Visonic peripherals (PIR motion sensors and 3rd party wireless add-ons, etc), I haven't worked with the PowerMax panel itself.
If I were there at your premises, I wouldn't have any qualms about finding a manual and troubleshooting the problem; but troubleshooting over the 'Net like this, I like to be sure of what I'm working with, exactly what the symptoms are, and what the manual for that particular panel says. Some brands change their programming protocol for every different model (Honeywell/Ademco being one of the few exceptions), so I'm reluctant to address programming issues without a model nomenclature and specific symptom(s).
Please let us know if your solution works out for you.