Problem in VIA SELECTION-SCREEN

I want to capture the output of standard transacion ih06 in internal table and  want to skip output of ih06 and show my desired output by processing it.

Problem : When I am running this code, after giving input and pressing F8, Then program remain on input selection screen only AND output is displayed only after clicking BACK BUTTON. How to avoid this.

CODE :

DATA list_tab TYPE TABLE OF abaplist.

SUBMIT RIIFLO20

VIA SELECTION-SCREEN

EXPORTING LIST TO MEMORY

AND RETURN.

CALL FUNCTION 'LIST_FROM_MEMORY'

   TABLES

     listobject = list_tab

   EXCEPTIONS

     not_found  = 1

     OTHERS     = 2.

IF sy-subrc = 0.

   CALL FUNCTION 'WRITE_LIST'

     TABLES

       listobject = list_tab.

ENDIF.