I am attempting to add a vertical line to a dynamic column chart. I've
followed the steps described by Jon Peltier at
http://peltiertech.com/Excel/Charts/...ertSeries.html
This procedure works fine until I change the base unit on the x-axis to
"Days." This causes the columns to turn into vertical lines (since each
monthly observation is really for, e.g., 6/1/2007).

If I leave the x-axis as monthly and then add the secondary x-axis for the
vertical (xy scatter) line, the scale on the secondary x-axis goes from
1/1/1900 - 12/1/2036, which shoves my vertical line far to the right of where
I need it to appear on the primary x-axis.

I realize I can manually alter the min and max of the secondary x-axis to be
the (numerical) equivalents of my min and max for the primary x-axis. But
since this is a dynamic chart, I'd prefer to have the scaling set
automatically instead of manually adjusting it every few months.

Any suggestions will be greatly appreciated.