Hi,

What type of chart do you have?
Are all 3 data sets in the same chart?

Cheers
Andy

--

Andy Pope, Microsoft MVP - Excel
http://www.andypope.info
"MJA" wrote in message
...
I have 3 sets of data for different conditions. When charted, 2 sets have
the
option to "add trendline", but the third set (with more "ups and downs' in
the data) does not have the option available. There are no empty cells in
the
source data nor are there multiple series on the chart. Any ideas why I
don't
have the ability to add a trendline on this set of data. At first, I
thought
it was perhaps because there isn't a high enough order in the polynomial
fit,
but paring down the data so there is only one peak did not help (that is,
add
trendline was still not an available action).