I see in your screenshot that the years you are working with in your data set are 2014 and 2015.
Due to the function in Basedate expression which is by default =today(), the expressions will try to calculate (based on the OrderDate field) the sum of sales of current year (2018 and that's because of today() function) versus previous year (2017). Since your data is based on 2014 and 2015 sales, then the result will be 0.
I think you need to analyse what years you want to work with, then maybe create some variables to hold those years; next you'll be able to use those variables in expressions with set analysis for example.
In the file attached, I left same options as before but I modified from the chart properties the expressions generated in the end. Nevertheless, I don't think this is the best option for you as your date references should be flexible. This is why I think you need to create some variables to implement an accurate logic for date analysis so that when new data comes in the application, your expressions will still make sense for the user.