Costum filter does not seem to work

Dear Forum,

Currently I just started using WEBI 4.1 SP 3 had a course an am capable te make simple reports. Currently I am trying to create a YTD filter for on of my reports. Using the following formula:

=If(Right([Max Month];2) = "01"; If([BookyearOffset] = 0; 0; 1); If([BookyearOffset] = 0; 1 ;0))

[Max Month] = Max([Month]) In Report

Month = yyyyMM

If the formula answer is "1" the report filter should show in that data in the report.

My problem is when I query multiple years of data only the dimensions that extist in the latest year are shown dimensions that exist in both year do not show when filtering the data.

Does anybody know a solution for this problem?

Regards,