Interactive Chart Display

Ok here's the file. The x-values for the chart are column A. Two series of values are plotted: cpb and cpa. When I click on a data point in one of these series I get a msgbox with the x-value and the value of the series. I also want the corresponding entry for bsz (when I click a cpb point) or asz (when I click a cpa point). What I have isn't working; specifically the
& "Sz=" & rngData.Cells(Arg2, Arg1)
part of

MsgBox """" & .SeriesCollection(Arg1).Name & """" & vbCrLf _
& "S = " & myX & vbCrLf _
& "V = " & myY & vbCrLf _
& "Sz=" & rngData.Cells(Arg2, Arg1)
Also I would like to be to add more columns later on between cpb and cpa so that when I click a point from cpb I see the corresponding data of the new column.

[the graph is on sheet2]

...Well, that's not quite it. I've attached another excel file, so we can attack a simpler version.
This file has only one data series on the chart (I'll add more later). When I click on a data point, I would like to see a message box with the x-values, values, and the bsz value. So, for example, when I click on the first point I would like to see a box that says "500, 30, 41." So far I can only get "500, 30." How do I display data from column C (bsz) in the msgBox also?

Ok, but I want "bsz" to always reference the column directly to the right of "V". I want to be able to add another series to the chart and get the corresponding info. Do I need a variable instead of "3" in "bsz=" & rngData.Cells(Arg2, 3))?

...Well, I've spent some time with it and admittedly im not quite sure which part extracts the data range. I think I know how to use offset, but it's the first step i'm stuck on.

Ok. I figured out an alternative. But one question remains: Is there a way to extract the row information for a data point? So that if, say, I click the third point in series one, I get a message with the row number of the data info. Note: the row number will not (in general) be the point number, so just returning arg2 (I have learned) will not work.