Issues with Due Date two weeks before

Dear Experts,

I am trying to create a formula which gives me JIRA issues due but two weeks ago.

We have the following formula:

/CumulativeSum([Measures].[Issues with due date])/

Sum(
{ PreviousPeriods([Time].CurrentHierarchyMember),
[Time].CurrentHierarchyMember },
[Measures].[Issues with due date]
)

Now I thought I can easily create “Issues with due date two weeks ago” or something like give me calculated sum instead of current / today but “two weeks ago”

Anybody has an idea?