Hide block in selection screen

REPORT  ztest.

TABLES: bkpf.

SELECTION-SCREEN BEGIN OF BLOCK blk WITH FRAME TITLE text-001.
PARAMETERS: p_bukrs LIKE t001-bukrs MODIF ID tst.
SELECT-OPTIONS: s_gjahr FOR bkpf-gjahr MODIF ID tst.
SELECTION-SCREEN END OF BLOCK blk.

SELECTION-SCREEN BEGIN OF BLOCK blk1 WITH FRAME TITLE text-002.
PARAMETERS: p_chk AS CHECKBOX USER-COMMAND uc.
SELECTION-SCREEN END OF BLOCK blk1.

AT SELECTION-SCREEN OUTPUT.
  LOOP AT SCREEN.
    IF screen-group1 EQ 'TST'.
      IF p_chk IS NOT INITIAL.
        screen-active = '0'.
      ELSE.
        screen-active = '1'.
      ENDIF.
    ENDIF.
    MODIFY SCREEN.
  ENDLOOP.