Changing icons in ALV tree

Question

Guys this is driving me crazy, i want to switch my icons in the entire tree  once i click on a function button, i did this code but it does update the icons , however i get sy-subrc = 0 once I execute method change_node  . what im doing wrong ? what Im missing ?
thank you.
data: l_node_key   type lvc_nkey,
        lt_node_key type lvc_t_nkey.
  data :l_wa_item_layout    type lvc_s_layi,
        lt_item_layout      type lvc_t_layi.
  data: l_wa_item_layout_c  type lvc_s_laci,
        lt_item_layout_c    type lvc_t_laci.
  data:   l_wa_outtab_line    type  zfi_enc_niveis.
  call method tree1->get_top_node
    importing
      e_node_key        = l_node_key
    exceptions
      cntl_system_error = 1
      failed            = 2
      others            = 3.
  if sy-subrc <> 0.
    message id sy-msgid type sy-msgty number sy-msgno
               with sy-msgv1 sy-msgv2 sy-msgv3 sy-msgv4.
  endif.
  call method tree1->get_subtree
    exporting
      i_node_key       = l_node_key
    importing
      et_subtree_nodes = lt_node_key.
  loop at lt_node_key into l_node_key.
    call method tree1->get_outtab_line
      exporting
        i_node_key     = l_node_key
      importing
        et_item_layout = lt_item_layout
        e_outtab_line  = l_wa_outtab_line.
    REFRESH: lt_item_layout_c.
    loop at   lt_item_layout into  l_wa_item_layout.
      move-corresponding l_wa_item_layout to l_wa_item_layout_c.
      if l_wa_item_layout-t_image = '@E4@'.
        move : '@GI@' to  l_wa_item_layout_c-t_image.
      else.
        move: '@E4@' to  l_wa_item_layout_c-t_image.
      endif.
      append l_wa_item_layout_c to lt_item_layout_c.
    endloop.
    CALL METHOD TREE1->change_node
        EXPORTING
          i_node_key     = l_node_key
          i_outtab_line  = l_wa_outtab_line
*       IS_NODE_LAYOUT = l_wa_item_layout_c
          it_item_layout = lt_item_layout_c
*          I_NODE_TEXT    =
*          I_U_NODE_TEXT  =
        EXCEPTIONS
          node_not_found = 1
          OTHERS         = 2.
      IF sy-subrc  = 0.
*       MESSAGE ID SY-MSGID TYPE SY-MSGTY NUMBER SY-MSGNO
*                  WITH SY-MSGV1 SY-MSGV2 SY-MSGV3 SY-MSGV4.
      ENDIF.
  endloop.
  call method TREE1->frontend_update.
Edited by: José  M. Sánchez on Nov 8, 2011 12:07 PM
I was missing move 'X' to l_wa_item_layout_c-u_
Edited by: José  M. Sánchez on Nov 8, 2011 2:15 PM

Answer 1

I had to move :
  move 'X' to l_wa_item_layout_c-U_T_IMAGE.
in other to update that value.