parameter substitution in queries takes place after running full query in BIRT

Question

Select count(Marks), ID from Student where From >= ? and to < ? group by ID.

I have this query in one of the data sets in BIRT. Now when i run the report and check "show full processlist", i am getting result as "Select count(Marks), ID from Student where From >= '' and to < '' group by ID" but after running multiple times it substitutes report parameters in to query.

How solve this problem?