How to apply filter at runtime in SSRS 2008 R2 In my report in SSRS 2008 I have created a expression for the CasesShipped column like this:

=IIF(Fields!Current_Product.Value= "Match"," ",Sum(Fields!Cases_Shipped.Value))


It sums the Cases_Shipped value having same distributor item code. Now I want to apply  a filter for the Cases_Shipped drop down list value to report records after previously mentioned activity.

How can I do this?
Probably the easiest way would be to use a drill through report. Add an action to the row group that links to a new report. Duplicate the layout of the new report, but implement a filter on the dataset of interest. 

Pass the row group value ([SQLFieldName]) to a parameter of the report. If you use a multivalue variable with an IN statement in the SQL, several filters can be used at once.