X-Axis Units Disappear in Stacked Area Chart (Excel 2007)
 

I have a stacked area chart that charts percentages over 12 months
(Jan-Dec). This chart also includes a data series of 100% (as a line
chart). Both series, one plotted as a stacked area, the other plotted
as a line chart type are on the primary axis.
The x-axis is set to display Jan-Dec. The y-axis is set to display the
percentages.
In the axis option I have set the unit choices to auto. When I save
and close the file that contains the chart and then re-open, the x-
axis only shows Jan on the x-axis. When I go back into the Axis
Options dialog box, the major unit, minor unit, and base unit options
are changed to fixed and show 77 for a value and month. I am not able
to figure out why it is changing that every time I open the file. Can
somebody help please?
All suggestions and comments are greatly appreciated.

TIA.
A. Crawford