Yes, there is a bug in XL in which for a line chart, it refuses to show
a break in the line. MS is aware of the problem, though I don't know
when (if?) it intends fixing it.
If you can substitute a XY Scatter chart for the Line chart, you can
still get the break(s).

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Tushar Mehta, MS MVP -- Excel
www.tushar-mehta.com
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> I created a chart in an earlier version of Excel (probably
> Excel 97). The Chart has one data series ploted as a line
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> How can I create a break in a line series for a selected
> data point.