Well, the issue doesn't seem to be resolved. Even when it was sorting the days before the weeks it was not sorting the days int he right order. Attached is a screen shot of what it is doing now. Starts at week 14 and goes to 1 then lists week 15 days. I want it to be in Descending order starting at the most recent week/day.
Your expression returns a String, and Strings are sorted just the way it shows - "15" goes before "2". If you have to use strings, you can at least format the Week number to always show 2 digits: