Hierarchical ALV Grid subtotal, total on a given column

Hi all,

i need to sum the subtotal and total of a column in a tree (3 heierarchies),subtotal of each hierarchy and total of all hierarchies in a given column. I have implemented the following for example

  fcat-fieldname   = 'SAFETY'.

  fcat-seltext_m   = 'Safety Stock'.

  fcat-col_pos     = 2.

  fcat-outputlen   = 10.

  fcat-emphasize   = 'X'.

  fcat-do_sum = 'X'.

but i am not seen the sum anywhere in the alv grid. Did i forget something? Thanks for your help.