Problema actualización de ALv a tabla interna

[javibest]

Tengo un ALV con check box y mostrado con la funcion

CALL FUNCTION 'REUSE_ALV_GRID_DISPLAY'
EXPORTING
i_callback_program = g_repid
i_callback_pf_status_set = 'SET_PF_STATUS'
i_callback_user_command = 'USER_COMMAND'
is_layout = gs_layout
it_fieldcat = t_fieldcat
* i_default = 'X'
* i_save = 'A'
TABLES
t_outtab = gt_alv.

El problema es que si marca el check box, luego en el user command, no me aparece la X en la tabla interna para saber que filas ha seleccionado.
Alguna idea ?

SAludos

[Bmamba]

Has marcado el campo box_fieldname de la estructura layout?

User command es del tipo:
FORM user_command USING $ucomm LIKE sy-ucomm
$selfield TYPE slis_selfield. ?

No se me ocurre sino.

haber yo lo hago con un list REUSE_ALV_LIST_DISPLAY y me funciona mira esto
CALL FUNCTION 'REUSE_ALV_LIST_DISPLAY'
EXPORTING
i_callback_program = g_repid
i_callback_pf_status_set = 'SET_STATUS'
i_callback_user_command = 'USER_COMMAND'
i_structure_name = 'TI_PLKO'
is_layout = gs_layout
it_fieldcat = gt_fieldcat[]
IT_EXCLUDING = gs_exclude[]
i_save = g_save
is_variant = g_variant
it_events = gt_events[]
is_print = gs_print
TABLES
t_outtab = TI_plko
EXCEPTIONS
program_error = 1
OTHERS = 2.

y en
l_tabname = 'TI_PLKO'.

CLEAR ls_fieldcat.
ls_fieldcat-fieldname = 'MARCA'.
ls_fieldcat-seltext_l = 'Selecc'.
ls_fieldcat-checkbox = 'X'.
ls_fieldcat-no_out = 'O'.
ls_fieldcat-input = 'X'.
ls_fieldcat-fix_column = 'X'.
ls_fieldcat-outputlen = 3.
APPEND ls_fieldcat TO lt_fieldcat.