After much trial and even more errors, I have determined:
1) there must be a selected cell somewhere in a workbook at all
times (that is, the only way to de-select a cell is to
select another)
2) sometimes a scatter plot created via VBA is a blank chart (no
source data, no series)
3) sometimes a scatter plot created via VBA contains 1 series with
the Y values set to the activecell

My question is...what is the factor that determines whether 2 or 3
listed above occurs? I create a scatter plot for 2 series and
sometimes get a 3rd blank one as well. The workaround is fairly
simple...if 3 series, delete the 3rd. But I really want to understand
this one.

Thanks,
John