You see a lot of old SaveAs code that does not specify the FileFormat
parameter. In Excel versions before Excel 2007, code without this parameter
will not cause too many problems because Excel will use the current FileFormat
of the existing file -- and the default FileFormat for new files is a normal workbook.
But because there are so many new file formats in Excel 2007-2010, we shouldn't
use code like this that does not specify the FileFormat parameter.
In Excel 2007-2010, SaveAs requires you to provide both the FileFormat parameter
and the correct file extension.
For example, in Excel 2007-2010, this will fail if the ActiveWorkbook is not an xlsm file
ActiveWorkbook.SaveAs "C:\ron.xlsm"
This code will always work
ActiveWorkbook.SaveAs "C:\ron.xlsm", fileformat:=52
' 52 = xlOpenXMLWorkbookMacroEnabled = xlsm (with macro's in 2007-2010)
These are the main file formats in Excel 2007-2010:
51 = xlOpenXMLWorkbook (without macro's in 2007-2010, xlsx)
52 = xlOpenXMLWorkbookMacroEnabled (with or without macro's in 2007-2010, xlsm)
50 = xlExcel12 (Excel Binary Workbook in 2007-2010 with or without macro's, xlsb)
56 = xlExcel8 (97-2003 format in Excel 2007-2010, xls)
Note: I always use the FileFormat numbers instead of the defined constants
in my code so that it will compile OK when I copy the code into an Excel
97-2003 workbook. (For example, Excel 97-2003 won't know what the
xlOpenXMLWorkbookMacroEnabled constant is.)