Reference a Cell in a Print Header/Footer

I have a spreadsheet that contains both Sheets and Charts and I want to Reference the contents of a cell in the header/footer of both types using VB.

The following Micosoft web site contains a nice simple piece of code that I would like to use if possible - uses the Workbook_BeforePrint method to add the cell contents to the header/footer before printing :-

http://support.microsoft.com/kb/273028

The following VB code works when printing a Sheet but not with a Chart.

Private Sub Workbook_BeforePrint(Cancel As Boolean)
   ActiveSheet.PageSetup.LeftFooter = Sheet1.Range("a1").Value
End Sub

I can make the code work with a Chart as follows

Private Sub Workbook_BeforePrint(Cancel As Boolean)
   ActiveChart.PageSetup.LeftFooter = Sheet1.Range("a1").Value
End Sub

My problem - if I combine the two I get an error because if the Sheet is active then the Chart is not, and the reverse of this, the Sheet/Chart that is not active generates the error in the code.

Private Sub Workbook_BeforePrint(Cancel As Boolean)
   ActiveSheet.PageSetup.LeftFooter = Sheet1.Range("a1").Value
   ActiveChart.PageSetup.LeftFooter = Sheet1.Range("a1").Value
End Sub

The ideal solution would be for a simple modification to the above code but I seem to be stuck hence any help would be appreciated.

Robert