Limit Date Dimension on Graph

[#1]

Hi All,

I have monthly data, but on the line chart I only want to display December 2014, December 2015 and the current selected period.

I created a calculated dimension and hard coded the dates.  How do I make the third data point dynamic to use the selected period.

=if(MonthName & ' ' & Year  = 'December 2014' or MonthName & ' ' & Year  = 'December 2015' or

MonthName & ' ' & Year  = 'May 2016',Month & ' ' & Year,Null)

[Gysbert_Wassenaar]

Can you post a small qlikview document that demonstrates the problem?