I would like to create a workbook in Excel 2011 for Mac that is fully usable in Excel 2003 (on Windows XP, Compatibility Pack installed).

The purpose is a semi-automatic calendar, where one enters holidays in one sheet and those days are automatically highlighted (as well as weekends) in other sheets. Here are links to the 2011 version and saved as Excel 97-2004 workbook. Feel free to open them to get an idea of what I'm talking about.

Now the point is that according to my targeted user the conditional formatting is lost in Excel 2003. I fired up the compatibility report and it **does** say that there are issues.

Workbook contains conditional formatting that cannot be displayed: Earlier versions of Excel cannot display data bars, color scales, and icon sets.

But there are no data bars, color scales or icon sets. I use a formula to set the font style and that's it. That's also what Excel 2003 should be capable of. The functions used in the formula are also available in Excel 2003: `INDIRECT`

, `MOD`

, `DATE`

, `MONTH`

, `IF`

, `AND`

, `OR`

, `MID`

, `CHOOSE`

, `WEEKDAY`

, `COUNTIF`

.

If I were to guess, I'd say that Excel 2011 inserts one of those things (data bars, color scales, icon sets) automatically. But then again, there are no other rules than my own. And there are only 3 of them, so that shouldn't be a problem either.

Do you have an idea what could be wrong? Could you please help me spotting the error?

Thanks in advance!