Total open issues in Backlog in a given time-frame

Hi there,

im trying to do a backlog burn-up for a given timeframe (e.g. 3 months) to see how many total issues we have and how we are progressing towards that scope.

Here is the code that I have, which works pretty well up until the current date:

[Measures].[Backlog]=
Cache(
Sum(
PreviousPeriods([Time].CurrentHierarchyMember),
[Measures].[Issue due]+
[Measures].[Issue created]-
[Measures].[Issue resolved]-
[Measures].[Issue closed count]
)
)
It works until the current date. But after that the sum should continue flat because in the future we don’t have issues created. What do I need to change to get that?

Thank you,
Sven