Hi Ehsan,
Welcome to this Microsoft Project newsgroup
Summaries are calculated by Project based on the indenting you use. A
filter can only show related summaries and cannot have its own summary.
However, you could create a hammock task to span the filtered task. To do
this it would be best to create a milstone linked to the first task and
another linked to the last task. Create the hammock between them. Then you
would have to include in the hammock whatever parameter you're filtering on.
Please see FAQ Item: 19. Hammock Tasks.
FAQs, companion products and other useful Project information can be seen at
this web address:
http://project.mvps.org/faqs.htm
Hope this helps - please let us know how you get on
Mike Glen
Project MVP
See
http://tinyurl.com/2xbhc for Project Tutorials