Here's what I'm trying to do. I relate two data sources by date, however one has data for a longer period. So let's say one has a full month and one just 15 days, same month same year. They bot have a measure each which are somehow related but not the same. What I would like to do is plot the two measures with dual axing and then forecast them for a certain period (let's say a week) each. Which can't happen apparently. Tableau will only plot the one with the longer period an say it can't plot the other since it contains nulls. Is there a workaround to this. It really makes forecasting a pain in the ***. Also a combine calculation between the sources, like "if isnull(Mesure1) then Measure2 else Measure1 end" will show the shortest period instead of attaching the second measure to the line from the 1st measure. If there's anything that can be done about this it will greatly impact my BI reports. Any help or clarifications on the issue are greatly appreciated. Thank you all in advance.