If you use NA() instead of "" in your formula, XL will interpolate that
point. The only way to create a gap in a XY Scatter chart (any version
of XL that supports VBA) or a line chart (prior to XL2002) is to use a
programmatic solution such as 'Chart gap for N/A' (http://www.tushar-
mehta.com/excel/software/na_discontinuity/index.html)

Note that XL2002 introduced a bug wherein a single segment in a line
chart cannot be formatted to 'nothing'. MS hasn't fixed the bug as of
2003.

--
Regards,

Tushar Mehta
www.tushar-mehta.com
Excel, PowerPoint, and VBA add-ins, tutorials
Custom MS Office productivity solutions

In article ,
says...
How do I keep a line chart from plotting blank cells. Formulas are in cells
that return a blank when false.