How to put lines on a column chart

[rdionne]

I am using a column chart to display my histogram data. I need to put some vertical lines ontop of the chart to show data limits.
I tried doing this with a combination line-column chart, but I couldn't figure out how to add the vertical lines. I also tried adding a line shape object, but I don't know how to place the line at the right places.
ActiveChart.Shapes.AddLine takes it's arguments in points and the x axis range changes from chart to chart. Help please.

 

[rdionne]

I figured it out. Say my data series goes from 20 to 80, plotarea.width=400, and I
want to place a line at 35.
Placement I want =
20 + ((35 - 20)/(80-20))*(400)= 120
Would it be better to do a combination chart than adding the shapes? I don't know how to do the combo chart.
RD