When a formula returns a zero value, the zero value is not being
displayed.

I have reviewed the following:
- conditional formatting
- zero values are checked (Tools/Options/View)
- stepped through my VB code (it inserts formulae based on a Worksheet
Change event)
- locked and hidden values unchecked with and without protection (this
should have no effect when the sheet is unprotected)

Are there any other circumstances that result in a zero value not being
displayed? Are there any other reasons for this occurrence?

Cheers
John