I have some spreadsheets with custon functions. They are stored in a module
when looking at the VBA window. These functions worked in 2003, but don't
seem to be recognized when I open the spreadsheet in 2007.

Here is one function:

Function GreatCircle(Satlong, ESlatN, ESlongE)
Convert = 180 / Application.Pi
GreatCircle = Convert * Application.Acos(Cos(ESlatN / Convert) *
Cos((ESlongE - Satlong) / Convert))

End Function

What should I be looking for?