Originally Posted by Katie Reynolds

That's a good thought, but as it turns out I don't think it will work because I have a formula in the cell. The formula sets the cell value to =NA() if there is no data available.

So when I opened your file (in Excel 2010), I tried putting =NA() and "" in the cell, and each time, it drew the line instead of leaving a hole.

Anyway, I think what I'm going to end up doing is putting the data in a bar graph instead of a line graph, so the empty spaces will for sure be empty. (The line is a running average trend line.)

An alternate solution was to make a macro that deleted the contents of any cells without data and connect it to a button on the sheet.

Anyway, thanks for your help!