You need to put the macro in the workbook's ThisWorkbook code module.

In article ,
OlieH wrote:

Chuck, thanks for the post. I must be dense, but I created a macro, renamed
it (from macro1) to
Private Sub Workbook_Open()
msgbox "Workbook opened"
Stop
End Sub
This did not execute when I opened the workbook. I am using the Auto_Open,
but I do want to understand your method. THanks again. Olie