I've tried several colors that I know are supported in the Excel BIFF default palette and still no joy.
The colors are not the same in the Excel5 and Excel2007 files.
Try the following setting to see that they are not producing the same background color.
I understand that BIFF only has a 56 color palette -- which is fine, if I could just figure out how to assign a color setting to use the intended color.
Help is appreciated.