Have to create a time dimension for active sprint.
for reference: below one is closed sprint time dimension.
When building calculated members in dimensions (like Time, Spirit, Project, etc.), you should use only members from the dimension you are calculating. Do not mix members from different dimensions as this might give unreliable results in the report.
Please see the ground rules for calculate members: Calculated members in other dimensions.
You might want to use another approach for the report. If you want to show time on the report row that matches the selected sprint, use the “Time within Sprint” measure to filter corresponding rows. Here is explained this approach with an example: Sprint burn-down or burn-up chart.
Zane / support@eazyBI.com