Unable to format cells
 

In my Excel 2003 application, I select a range of cells and set a vertical
border. This also works in Excel 2007 until I save it from the latter into
the compatible format. If I then open it again with 2007, it's inoperative. I
select the range, right-click, then click on format cells and nothing
happens. If I open it again with 2003, it works. If I then save from 2003 and
then open it with 2007, it will work. Any ideas?