please help (using a2k)

I have a Main Report with 2 sub-reports.

Sub-Report 1 displayes some info from a table.

Sub-Report 2 (based on a Query) displays a Date, Description and a Currency VALUE.

In sub-Report 2's footer section I have unbound textbox to calculate the TOTAL(sum) of the Currency Value.

(The Main Report is GROUPED by an ID (Prim key) field)

What I want: In the Main-Report's Group Footer section I want to display the TOTAL(sum) of Sub-Report 2's footer section (the TOTAL currency Value).

I think i need a text box the the main report's footer section and reference it to sub-Report 2's textbox in it's footer section, but don't know how to do the "SUM OF" ??

Any help will be welcome.

Thank you.

Piet.