Thanks again for the reply, Jon.

I'm positive the data is of the proper format, since as I said in my second
post above, I created a brand-new chart based on the exact same data, and I
was able to get it working. Like I said, I think it must have been some
strange bug in the previous chart that was imported from Excel 2003.

"Jon Peltier" wrote:

By "hidden" I just meant not easy to find (in "Classic" Excel). The Chart
menu Chart Options Axes dialog just controls what type of axis you have.
To change the scale you then need to double click the axis to bring up the
Format Axis dialog and use the Scale tab.

In Excel 2007, when you change the axis type on the Axis Options dialog, the
controls to set the axis scale should change according to what axis type has
been selected. However, unlike in prior versions, if your category values
are not interpreted as numeric, Excel 2007 ignores your selection of a
date-scale axis and offers only the category scale options.

Check your category data. Make sure they are dates or other numerical
values.

- Jon
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Jon Peltier, Microsoft Excel MVP
Tutorials and Custom Solutions
Peltier Technical Services, Inc. - http://PeltierTech.com