Opening specific worksheet using macro- Help

Hi,
I'm having a problem to use the macro for opening a specific worksheet in a workbook. My plan to setup the workbook to open the first worksheet no matter which worksheet that was last saved and close.

What i have in mind is like below macros but it is not working.

Private Sub Workbook_Open()
Worksheets("Main").Activate
End Sub

Attached is the sample for the workbook.

Thanks for the help..