I would like to trigger full re-calculation (equivalent to CTRL-ALT-F9
or Application.CalculateFull) whenever I load a new workbook.

I have Excel 97 SR-2, so CalculateFull is not available to me.

I am working on a project where at present I need to manually do a
CTRL-ALT-F9 whenever I open an existing sheet, so I would like to
automate this.

I have created an add-in with the following procedure defined in the
workbook vba

Private Sub Workbook_Open()
Application.SendKeys ("^%{F9}")
DoEvents
Debug.Print ("Sent keys")
End Sub

Now I can see the message printed so the code has been excuted, but
there is no effect on the sheet : I still need to manually do
CTRL-ALT-F9 before the sheet is in the state I require.

The question is: why didn't the sheet receive the message to
re-calculate and what can I do to fix this?