Creating an auto-updating button icon thumbnail image from card snapshot

[Keith Clarke]

Hi folks,
I'm working on a presentation stack, which has a home card with a set of buttons with thumbnail images (as the icon) that navigate to other cards in the stack. The other cards are evolving, so I'm trying to create an auto-update script to renew the navigation button thumbnail icon images when the home page is re-opened. I'm guessing that the script should end-up in a pre-open card script and iterate through a list of buttons, but I'm trying to get one button to work first.

Can anyone advise on what am I doing incorrectly with this script?

on preOpenControl
   import snapshot from the rect of card "Example"
   set the icon of me to it
end preOpenControl  

Best,
Keith..