I have a scatter plot with thousands of points (markers only, no line), and
am plotting a second series as a line with only a few hundred points over the
same range of x-values (line only, no markers). I want the line to appear in
front, but Excel 2007 keeps putting the marker symbols in front, which
completely obscures the line.

I have tried changing the series order, but it makes no difference. In the
Chart Tools - Format - Arrange toolbar, there are "Bring to Front" and "Send
to back" buttons, but they are greyed out.

Suggestions?