Excel 2003 chart sheet disappears in Excel 2007
 

An Excel 2003 file has spreed sheets and chart sheets visible when opened
with Excel 2003, but some of the chart sheets are not present when the file
is opened in my Excel 2007 -- however, some are present! I sent the file to
someone else who has Excel 2007 and he is able to see all of the chart sheets
on his Excel 2007. What settings should I be tweaking to see all of the
chart sheets?