I'm baffled by this, has anyone else seen anything like it?

I had a mixed set of time series of congressional elections, with
vertical markers and horizontal lines thrown in, two curves, two sets of
vertical lines, and one horizontal line, all as a pure scatter chart
format, and I wanted to add a column series to provide shading bands for
presidential party in the same period, grey for one party and untouched
for the other. So I created a series of 1,0,0,1, etc. and added it to
the chart, giving it its own secondary y-axis, not because it needed one
but because it did need a second category x-axis (because all the other
series were using an interval x-axis, since they were XY points)

I had shrunk the gap between bars to zero and set the border to "none",
when I noticed that the bars were the opposite of where I expected them
to be, grey for the party I had wanted blank, and blank where I wanted
grey; so I brought the borders and gaps back, and sure enough the
columns were where there were supposed to be no columns, and vice versa.
Even more bizarre, when I brought the tops of the columns down into
view, columns started in mid air where the data should have ended! I
have columns that are photographic negatives of the data!

I haven't time to post an example chart or spreadsheet, but may later if
anyone needs it, or I can email. But has anyone encountered this, what
looks like a plain and simple bug to me?

I am using Excel 97 on Windows XP.

--
Del Cotter
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