Date grouping parameter problem in line graph

Summary

If I select "Month" as the grouping parameter my line graph shows 0 for months that are outside of the date_range filter

Content

Hi everyone,

I am attempting to copy report ID#85 Incident Trend and change it to a line graph.

Everything seems to be working well except for 1 issue.

If I select "Month" as the date grouping I get the intervals 01, 02,03,...12 even though my date range filter is for incidents created in the last six months. The filter works, so for intervals 01, 02,03,04,11,12 the values are all 0. 

My question: How can I restrict the graph to only show non null intervals?