looping screen

Dear Experts,

SELECTION-SCREEN begin of block k with frame TITLE text-001.
  PARAMETERS : r1 RADIOBUTTON GROUP g MODIF ID g1,
               r2 RADIOBUTTON GROUP g MODIF ID g2.
  SELECTION-SCREEN end of block k.




  SELECTION-SCREEN begin of block k1 with frame TITLE text-002.
  PARAMETERS : pernr type pa0001-pernr.
  SELECTION-SCREEN end of block k1.



  START-OF-SELECTION.
  loop at screen.
  if screen-group1 = 'G1'.
    screen-invisible = 0.
    endif.
    MODIFY SCREEN.
    endloop.

when i click on first radio button the second selection screen should disapper so what to do for this can any one help me.

Thanks and Regards,

Thirukumaran. R