Pass Value from one DataSet to another DataSet to filter row in Reporting Services 2008

I have 2 table stacked at a single page,one for filtering previous year and 2nd table for the current year and i pass in the same value from the DataSet to these two table , the only difference is that i need to filter it with the year using the Tablix Properties. Right now i am filtering the Year with the hardcoded value like 2008,2009 for 2nd table. I planned to do it dynamically, so i created another DataSet (DS2) and tried to put it in the fx(Expression) as =First(Fields!Year1.Value, "DataSet2") in the开发者_运维技巧 Filter in the Value Textbox just like the diagram. but i get

Error as : A FilterValue for the tablix ‘Tablix1’ includes an aggregate function.  
          Aggregate functions cannot be used in dataset filters or data region filters.

i tried to use parameters, but it doen't return any table. any help would be appreciated.

Do you want to calculate the years relative to the date the report is run?

That would be easier as the function Value would then be something like

=Year(DateAdd("Year",-1,Now())

for -1 for last year, -2 for two years ago etc.