A family of Microsoft spreadsheet software with tools for analyzing, charting, and communicating data.
Sheet1 is the code name. Its sheet name is June 19. So use either
Private Sub Workbook_Open()
If Worksheets("June 19").Range("O2") = "" Then
MsgBox "hello"
End If
End Sub
or
Private Sub Workbook_Open()
If Sheet1.Range("O2") = "" Then
MsgBox "hello"
End If
End Sub