A smooth line makes sense only for a Line chart or a XY Scatter chart
-- basically, charts that have a marker of some kind.

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Regards,

Tushar Mehta
www.tushar-mehta.com
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In article ,
says...
I have a Histogram chart that I am trying to add a smooth line to. According
to help I select the data series, go to the format series section, then the
Pattern Tab and select the Smooth check box but there is no Smooth check box.
What am I doing wrong? Any suggestions?