table edit - itab not getting updated with new value

I am using a tableview iterator to edit a particular column. I am trying to edit a column and post it to a table in BW. Once I enter a new value and submit, it goes to oninputprocessing page with the following code. However, the new value is not getting posted. The itab3 doesn't even get populated with the new value I enter. What's wrong with this code? Thanks.

CLASS cl_htmlb_manager DEFINITION LOAD.

DATA: event TYPE REF TO cl_htmlb_event.
DATA TEST TYPE P DECIMALS 2.

event = CL_HTMLB_MANAGER=>get_event( runtime->server->request ).
if event->id = 'Update' and event->event_type = 'click'.
  DATA: tv TYPE REF TO cl_htmlb_tableview.

FIELD-SYMBOLS <i> LIKE LINE OF selectedrowindextable.

tv ?= cl_htmlb_manager=>get_data( request = runtime->server->request
                                 name = 'tableView'
                                 id = 'tv1' ).

IF tv IS NOT INITIAL.

DATA: tv_data TYPE REF TO cl_htmlb_event_tableview.
  tv_data = tv->data.
  refresh itab2.
  refresh itab3.
  call method tv_data->GET_ROWS_SELECTED
  receiving selected_rows = itab2.
  endif.
  data : ind type SELECTEDROW,
          row_s type row.

  if itab2 is not initial.
    data: rw LIKE LINE OF itab.

    loop at itab2 into ind.
    READ TABLE itab INDEX ind-index into
    rw.
    if rw is not initial.
    row_s = rw.
    append row_s to itab3.
    clear row_s.
    endif.
    endloop.




        MODIFY ZNCNO013 FROM table itab3.


if sy-subrc = 0.
COMMIT WORK.
endif.

      ENDIF.
      endif.