I'm developing a report that displays and editable ALV. 

I set PF-STATUS, adding a 'Process' button. When this button is pressed, the content introduced in the ALV by the user should be retrieved and then processed. 

This is how I'm building my ALV:

```
CALL FUNCTION 'REUSE_ALV_GRID_DISPLAY'
EXPORTING
  i_callback_program       = sy-repid "program name
  i_callback_user_command  = 'USER_COMMAND' "user command subroutine name
  i_callback_pf_status_set = 'SUB_PF_STATUS'
  it_fieldcat              = it_fieldcat
  i_save                   = 'X'
TABLES
  t_outtab                 = it_input
EXCEPTIONS
  program_error            = 1
  OTHERS                   = 2.

```

However, the way I'm doing this, the retrieval comes empty. 
How can I solve this problem? 

Below I have a snippet of my code when it comes to 'Process'.

```
IF r_ucomm EQ '&PROC'.

 LOOP AT it_input INTO ls_input.
   PERFORM process_data USING ls_input.
 ENDLOOP.

ENDIF.

```