Managing relationships with two months and two tables

Hi,

I just learned about managing relationships, but I'm still confused on what it does. I have two tables that I want to compare monthly data for different tables. I only want to see the months in the date hierarchy in my visual. However, when I click put both of my months in the y-axis my visual looks like this: 

I'm not sure why it is showing all of the months of the year. There is only data for July (1st table) and August (2nd table). Is this something that can be fixed with the managing relationships tool?

Thank you,

Chris