Window Navigation on a template

I am using the script below for a mouse click script on a LED Display, I have a custom property named WindowPath. But I get an error saying the window doesn’t exist.

window = system.nav.openWindow(event.source.parent.WindowPath)

Try printing event.source.parent.WindowPath.

I changed the custom property name and it worked?!

window = system.nav.openWindow(event.source.parent.Path)