Division by 0 (zero) in an App

[Han]

It is fairly evident that the HeatIndex() function does absolutely nothing since there is no code there (just an empty BEGIN END; block).

The actual code that starts your app is the START() function that has been _ALSO_ duplicated as a [View] menu item, listed as "Start HeatIndex".

So the function you want to export (if that is in fact what you want to do) is the START() function.