Before this post, better read previous about cell address.
Here are a sample on writing formula in a cell:
myRange.Cells(2, 2).Formula = “=SUM(A1:A4)”
More: localization may get you some headache, so True/False better be written in english, and parameters my be “,” separated, not “;” . 
source: Office Space: Tips and Tricks for Scripting Microsoft Office Applications
