in Main Report I have make formula by the name of @a, then
in sub of report I make formula by the name of @b.
then I wish to make new in main report with the name @c.
where value of formul @c is @a-@b.
but formula @b in subreport,
I can't to use/ not show in main report.
how I can take formula @b which in subreport.
thank's