I have a line chart with date values on the x axis. I want to add vertical
marker lines on the chart to show when certain events happened (which do not
correspond to dates for which there is data in the line chart). I did a
websearch and supposedly you can do this with something called the "series
method", so I tried that. It worked all right, except where my vertical bar
showed up on the chart was nowhere near the date that I'd assigned to it;
hence, not very useful. I tried the "error bar method" and the results were
even more ghastly and useless. Is there a method for doing this that
actually works?

Thanks,