Need help comparing Datespans

I have a data slicer where I can select a datespan and a table with roughly the following layout:

I want to have two line diagrams. Both are suppose to have dates as their axis. The first one should show the amount of unfinished invoices and the second one the average age of invoices in the selected datespan.

I have tried a couple of times but don't manage to get it working. I'm thankful for any kind of help.