I have used this code for disable of shipped status but in output it still shows as editable for shipped status

I want exact solution to make particular field for status shipped as disabled.
LOOP AT IT_FINAL INTO WA_FINAL.
IF WA_FINAL-STATUS = 'PACKED'.
ls_stylerow-fieldname = 'NOTE' .
ls_stylerow-style = cl_gui_alv_grid=>mc_style_enabled.
APPEND ls_stylerow TO wa_FINAL-field_style.
MODIFY IT_FINAL FROM wa_FINAL TRANSPORTING field_style.
elseif wa_FINAL-STATUS = 'SHIPPED'.
ls_stylerow-fieldname = 'NOTE' .
ls_stylerow-style = cl_gui_alv_grid=>mc_style_disabled.
APPEND ls_stylerow TO wa_FINAL-field_style.
MODIFY it_FINAL FROM wa_FINAL TRANSPORTING field_style.
ENDIF.