How to get sales in the last 5 weeks

[#1]

Good afternoon

How can I get sales from the last 5 weeks, having the following data:

sum({<Fiscal_Week={'>=$(=max(Fiscal_Week,-5))<=$(=max(Fiscal_Week))'}Ventas)

I am applying the following set of analysis

But he does not show me anything

How should I express my analysis set?

Thank you

[sunny_talwar]

May be create a numerical Fiscal_Week in the script to use in set analysis, the one above seems to be text and you cannot find min/max of a text field...