Ashley,
According to the Help file, using the XL5 option limits you to Excel speadsheets created by Version 5.0 - the one in Office 95. If the spreadsheet comes from Excel 97 (version 8.0), and you have VFP 6.0, use XL8. If it comes from Excel 2000 (version 9.0) it "may" work using XL8 - but no guarantees.
You may have to resort to using the Excel ODBC driver, and reading the data this way - I've never done it, although I know it's been done.
Rick