The first part: >=$(vWeek7) works correctly, as you can see from the screenshot below:
However, as you can see above, the second part: <=date(vWeek7+6, 'DD/MM/YYYY') is not working. I used this individual bit in another expression it works, where I only want to know data for week 7 + 6 days. However, when being used in this between expression, it is being ignored.