How to prevent a line chart from having a blank spot or also dropping to zero when there is a blank cell or a zero value that should be blank cell.
Here is the problem:
If you have zeros in your data that you are using to represent a blank value, the chart will not understand this and will, instead, represent it as zero in the chart.
As such, DO NOT use a zero to denote emptiness in a set of data that you will put into a chart or it won't look right.
Download the accompanying spreadsheet to see this in Excel.