Show delta value between two line graphs

Friends,

Need help. In a typical line graph where there are two lines, wondering how to represent the difference between each data point in the graph.

For eg:
X-axis: Jan, Feb, Mar etc..
Y-axis: $ amounts from $10 to $100

Data: Between two sales offices, show the $ for each month as line graphs.

What is required: The delta portion between two line graphs - say for Jan - if the difference in amount is $5, then I want a dotted line connecting both dots and show this amount as difference amount. How can we achieve it?

Good one. But its not clear how does the line in the middle come up.. the middle line graph turns into a vertical line..how does this happen?

Am using Excel 2013. How do I configure the 'Secondary X-axis' labels?

I got the hi lo lines. But I tried using that procedure.. I couldn't get the diff number right in between the two line graphs. Can you pls help. Here is my data:

Role Series A Series B Diff Label
2B $23.10 $11.30 17.2 $(12)
3A $23.10 $13.77 18.435 $(9)
3B $23.10 $16.30 19.7 $(7)
4A $23.10 $18.00 20.55 $(5)
4A $23.10 $20.00 21.55 $(3)
4B $23.10 $19.00 21.05 $(4)
4B $23.10 $15.54 19.32 $(8)
5A $23.10 $19.00 21.05 $(4)
5B $23.10 $22.00 22.55 $(1)

Hi,

How do you expand the data set down on this example? On your kindly uploaded document, it is to rows deep and so the graph only runs to 9 entries. When i have tried to expand this in the select data series, and or when i have tried to edit the data series Horizontal (category) Axis Labels, it wont let me add additional? i need the table to expand to 35 lines of data in the graph? Other than that, this works perfectly for me