Konnected PRO with Interface - Can unused ZONES be used by Konnected for OUTPUT?

Recently got my Konnected PRO with the Interface option.  Mostly have everything working, but wanted to add a Piezo for Chime in area of house where Panel is.  

I have Vista20P with 8 zones.  Konnected PRO supports 12.  This leaves 4 zones on Konnected board unused.  I have already used both of my OUTPUTs on Pro Board with my relays to ARM STAY/AWAY modes.   

I would like to use one of my unused PRO Zones as Output 3.3V to wire a Piezo Buzzer.  I may also like to add a new contact switch and maybe a motion detect at some point in the future.  Yes, I understand these new switches/motion detectors wouldn't be available to my Vista20P, but is there any reason I couldn't wire them for use with the Konnected PRO empty unused zones?  

My immediate task is the Piezo buzzer.   I have the positive side connected to an unused Konnected Pro zone, and negative to common ground.  Is this valid?   I cannot seem to get Piezo to fire, and wondering if I'm expecting the product to do something it wasn't designed for.   

In general, are those 4 unused zones useable in the PRO when using the Interface integration?  Do all zones have to be in Traditional system to be used with Connected? 

If so, any ideas what I might be doing wrong?  Has anyone done something similar successfully? 

Did you get anywhere? I am about to see what I can do with 4 unused zones on the 2nd interface board. I am assuming the interface board is referenced to 12v alarm panel aux so any additional sensors would need to also be similar