Creating Report Server 2005 Report Totals

I have a table in my report. In it, I have 2 headers, a group and 1 footer at the bottom.

How do I sum my columns in the footer?

so nobody has tried adding totals in a table before or what?|||Uhm. Why don't you try
=sum(Fields!MyFieldToSum.Value)
typed in the footer field? Or do I miss something here?