Update likp CHANGEDOCUMENT_SINGLE_CASE: Problem NOT updating

Hi.

I need to update likp with changesdocument_single_case to have the changes log.

I'm using this

      CALL FUNCTION 'CHANGEDOCUMENT_SINGLE_CASE'
        EXPORTING  TABLENAME           = 'LIKP'
                   WORKAREA_OLD        = ld_old_likp        "old values
                   WORKAREA_NEW        = ld_changed_likp    "new values
                   CHANGE_INDICATOR    = 'U'                "Update_LIKP'
                   DOCU_DELETE         = ' '
        EXCEPTIONS NAMETAB_ERROR       = 1
                   OPEN_MISSING        = 2
                   POSITION_INSERT_FAILED = 3
                   OTHERS              = 4.

Any idea why this is not working?