Check_Changed_Data not working

Hi all,

In my BADI i am triggering an ALV grid pop-up to select values with check box. For getting the changed data i am using check_changed_data method. Even after selecting the check boxes in ALV pop i am not able to get the changed data.

program code :

CALL FUNCTION 'REUSE_ALV_GRID_DISPLAY'
    EXPORTING
      i_callback_program    = sy-repid
      i_grid_title          = 'Select MAil ID'
      is_layout             = lt_layout
      it_fieldcat           = t_fieldcat
      i_screen_start_column = 20
      i_screen_start_line   = 5
      i_screen_end_column   = 70
      i_screen_end_line     = 15
      I_SAVE                = 'A'
    TABLES
      t_outtab              = it_ZEMAIL
    EXCEPTIONS
      program_error         = 1
      OTHERS                = 2.
  IF sy-subrc <> 0.

  ENDIF.


data: gd_repid like sy-repid,
        ref_grid type ref to cl_gui_alv_grid.

  if ref_grid is initial.
    call function 'GET_GLOBALS_FROM_SLVC_FULLSCR'
      importing
        e_grid = ref_grid.
  endif.
  if not ref_grid is initial.
    call method ref_grid->check_changed_data .
  endif.

while debugging i found that the ref_grid remains initial after the function GET_GLOBALS_FROM_SLVC_FULLSCR.

so call method ref_grid->check_changed_data is not executed.

So how can i solve this problem.

Thanks in advance.

Venkat.