Need help using hierarchical list with class cl_salv_hierseq_table

Question

I'm trying to learn how to use a hierarchical avl.
so I grabbed this code http://wiki.sdn.sap.com/wiki/display/Snippets/displaysimplehirarchiallistwithclass+cl_salv_hierseq_table
and changed it in order to use the tables bkpf and bseg instead

Answer 1

TABLES: bkpf.
TYPES: BEGIN OF ty_bkpf ,
       belnr LIKE bkpf-belnr,
       bukrs LIKE bkpf-bukrs,
       gjahr LIKE bkpf-gjahr,
       bldat LIKE bkpf-bldat,
       waers LIKE bkpf-waers,
       END OF ty_bkpf.
TYPES: BEGIN OF ty_bseg ,
       buzei LIKE bseg-buzei,
       shkzg LIKE bseg-shkzg,
       END OF ty_bseg.
DATA: it_bkpf TYPE STANDARD TABLE OF ty_bkpf ,
      it_bseg TYPE STANDARD TABLE OF ty_bseg .
DATA: ibinding TYPE salv_t_hierseq_binding.
DATA: xbinding TYPE salv_s_hierseq_binding.
DATA: gr_table TYPE REF TO cl_salv_hierseq_table.
SELECT-OPTIONS:
  ndoc FOR bkpf-belnr,
  empr FOR bkpf-bukrs,
  anod FOR bkpf-gjahr.
START-OF-SELECTION.
  PERFORM get_data.
  PERFORM relat_tables.
  PERFORM display_alv.
*&      Form  get_data
FORM get_data .
  SELECT belnr bukrs gjahr bldat waers
         INTO TABLE it_bkpf
         FROM bkpf
         WHERE belnr IN  ndoc AND
               bukrs IN empr AND
               gjahr IN anod.
  IF sy-subrc = 0.
    SELECT buzei shkzg
           FROM bseg
           INTO TABLE it_bseg
           FOR ALL ENTRIES IN it_bkpf
           WHERE belnr = it_bkpf-belnr AND
                 bukrs = it_bkpf-bukrs AND
                 gjahr = it_bkpf-gjahr.
  ENDIF.
ENDFORM." get_data
*&      Form  relat_tables
FORM relat_tables .
  xbinding-master = 'BUKRS'.
  xbinding-slave  = 'BUKRS'.
  APPEND xbinding TO ibinding.
ENDFORM. " relat_tables
*&      Form  display_alv
FORM display_alv .
  cl_salv_hierseq_table=>factory(
  EXPORTING
  t_binding_level1_level2 = ibinding
  IMPORTING
  r_hierseq = gr_table
  CHANGING
  t_table_level1 = it_bkpf
  t_table_level2 = it_bseg
  gr_table->display( ).
ENDFORM. " display_alv