Excel 2003 :: Shared Workbook - Add Button To Worksheet

I've added some code the adds a button to a worksheet

Public Sub AddSheetPrintButton()
Dim btn As Button
Dim t As Range
Set t = ActiveSheet.Range(Cells(1, 6), Cells(1, 7)) ' button position
Set btn = ActiveSheet.Buttons.Add(t.Left, t.Top, t.Width, t.Height)
With btn
.OnAction = "sheetPrint"
.Caption = "Print Sheet"
.Name = "Print"
.Font.ColorIndex = 10
End With
End Sub

This works fine until the workbook is shared!