Dysplay horizontal grid lines Alv

Hi,

I try to display horizontal lines in alv oo when I print it.

I try to use

    CALL METHOD gr_alvgrid->set_horizontal_grid_lines
      EXPORTING
        visible = X
      EXCEPTIONS
        error   = 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.

but I have this error:bold Access to protected method "SET_HORIZONTAL_GRID_LINES" is not allowed. bold

Can I solve it?

Thanks!!!