Drill down doesn't work after upgrade

[adik]

hi all,
i have a report that works as expected in cognos 8.3, but since the upgrade to 10.2 thing have gone amok.
the issue here in question is the following:
i have a time tree prompt with the following levels: All -> Year -> Quarter -> Month -> Day and the data item called Time, based on this tree prompt defined as: set([Dimensional View].[Time].[Time] -> ?p_Data?)
i then have a data item called Last Day, based on the selection from this tree prompt that computes the last day of the selected time defined as: closingPeriod ([Dimensional View].[Time].[Time].[Day], currentMember([Dimensional View].[Time].[Time]))

the report layout is that both Time and Last Day are on the columns and Last Day is placed under Time. the expected behaviour is that i select a date (i can select all, year, month and so on) and based on this i get the Last Day calculated and the measure is then filtered based on the Last Day.

the drill-up and drill-down for both Time and Last Day is set to Replace Expression in cognos 8.3 and it works fine
in cognos 10.2 the drills don't work anymore, the data items don't appear as hyperlinks and i cannot drill-down if i click on Time data item.

has anyone else encountered this? any advise is welcome!

thanks