When trying to open an XLSX or XLSM file with ExcelApplication, you get the following error message:
This file does not appear to be a valid Excel 97 or later binary file. Please try opening in Excel 97 later by saving as “Microsoft Excel Workbook (*.xls)”
Support for the Office 2007/2010 file formats (XLSX, XLSM) was introduced for ExcelApplication in ExcelWriter 8. Earlier versions with throw the above exception when attempting to open an XLSX file with ExcelApplication.