why does "Private Sub Workbook_open" not work?

Im trying to get Excel to load some formulas when the workbook opens, however it doesn't. Why would this be?

here's an example

Private Sub workbook_open()
Sheets(2).Range("B19").Formula = "=B17"
End sub

Ive tried it in the module and where you can code for the indivudual page. Do you have to create a macro?

when i do 2 it works fine. when i add more than that i get this error

Run time error '1004':
Application-defined or object-defined error

I am so confused

add more formulas such using this just changing numbers:

Sheets(2).Range("B19").Formula = "=B17"

and get the error i posted above

I will suggest to attach a example sheet with your post. So that we can debug it.

I cant get it to come up in a sample spreadsheet... i dont know

Ok it has something to do with my spreadsheet. im going to have to start over.

thanks for the help