"Last Closed Sprint" is displaying old sprints

Hi,
i have a report that uses, a row, a calculated member for “Last Closed Sprint”.

  1. In the beginning, I closed sprint A and opened B and the result showed me sprint A results. This is good.
  2. Then closed B and opened C. i expected to see B results, but now i have two rows. on the “last closed sprint” (i.e. B) and one for A.
  3. When i closed C and open D i will have A, B and C as the “Last closed Sprint”.

for (2) i want to see only B and for (3) only C.

This is how “Last Closed Sprint” is defined:
Aggregate(
Tail(Order(
Filter(ChildrenSet([Sprint].[MyBoard]),
[Sprint].CurrentHierarchyMember.getBoolean(‘Closed’) AND
NOT IsEmpty([Sprint].CurrentHierarchyMember.get(‘Complete date’))),
[Sprint].CurrentHierarchyMember.get(‘Start date’),
BASC
), 1)
)