Data is missing for a some of the months when i dilled down to year month

[RamBhagure]

I have production data of day-to-day basis; I have two sheets first contains production data and second one is contained the managers email of different unit. For monitoring the production, I have plotted time series graph, when i plotted this graph, all things are working well, but when I blended the manager sheet the problem arises, The problem is production data of some of the months are missing, but at the same time when I drilled down to the date all data is available on date but in year month it is showing zero for some of the months.

[sam8]

There is likely some issue in the blend. Selecting "full outer" might help you preserve data! 

Feel free to share your join condition(s) here as well, it might provide us more insight on the problem.