This is a problem that's been discussed before, but I haven't seen this
aspect addressed: If you select the chart in question and go to
ExcelPreferencesChart, you can indicate that empty cells should be
plotted as 'Not plotted (leave gaps)". (This is one of 3 options
including "Zero" and "Interpolated".) Thing is, this doesn't work!

As far as I'm able to determine, the ONLY thing that Excel will do is
treat your blank cells as zero values (yeah, yeah, unless I replace
those blank cells with "#N/A"). The work-arounds are fine, but why
won't Excel do what it's supposed to? Any chance they'll fix this?

Thanks, Pete

Microsoft Excel 2004 for Mac, ver 11.2.3