It is possible that the columns are formatted as text (or the data were
somehow entered as text). Select the entire column and then Format |
Cells... | Number tab. Ensure you have 'General' selected. Next, copy
any empty cell. Now, select the cells containing the data you want to
plot. Then, do Edit | Paste Special... | In the Operation section
select Add the click OK. Now, try creating the chart again.

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Regards,

Tushar Mehta
www.tushar-mehta.com
Excel, PowerPoint, and VBA add-ins, tutorials
Custom MS Office productivity solutions

In article ,
says...
I am trying to plot two values for each day on a line chart. I have followed
procedures that I have used in other line charts that is clicking on the
range of values I want, but all I get is the two axis not values - could
someone help me out on this one ??