Item on the listbox cant be selected. PLS HELP.

Question

hello! i am a newbie to ABAP development.
I followed the listbox steps stated on the RSDEMO_DROPDOWN_LISTBOX because I want to populate my listbox (I created from the screen painter) with the data from a table. It was successful and I can see the data now. Problem is when I am selecting an item of the listbox, it wont be selected. the only thing always selected is the first item on the listbox? what is happening? I do not understand. PLS HELP.
big thanks.
TYPE-POOLS: VRM.
DATA: VALUE TYPE VRM_VALUES WITH HEADER LINE.
DATA: DD1(20).
DATA: INT_SPFLI LIKE SPFLI OCCURS 10 WITH HEADER LINE.
SELECT * FROM SPFLI INTO TABLE INT_SPFLI.
START-OF-SELECTION.
  SET SCREEN 100.
MODULE PBO OUTPUT.
  LOOP AT INT_SPFLI.
    VALUE-TEXT = INT_SPFLI-CITYFROM.
    APPEND VALUE.
  ENDLOOP.
   CALL FUNCTION 'VRM_SET_VALUES'
    EXPORTING
          ID     = 'DD1'
          VALUES = VALUE[].
ENDMODULE.
MODULE PAI INPUT.
  CASE SY-UCOMM.
    WHEN 'BTNEXIT'.
      LEAVE PROGRAM.
  ENDCASE.
ENDMODULE.

Answer 1

<b>THIS IS A FOLLOW UP QUESTION.</b>
I have listbox DD1 and I populated that with SPFLI-CITYFROM data. I used SELECT DISTINCT statement so that it will not repeat same entry on my list box. It was successful but then on the 2nd time and on the succeeding times you click on the listbox (trying to select other item), the listbox shows all the city entries from the SPFLI-CITYFROM. The SELECT DISTINCT takes effect only at first because as I have said on the 2nd and succeeding times you click the listbox, it will show you all entries of  SPFLI-CITYFROM. why is that? i dont understand.
im sorry if i sound so dumb. im a newbie.<b> big thanks to all. </b>
TYPE-POOLS: VRM.
DATA: VALUE TYPE VRM_VALUES WITH HEADER LINE.
DATA: DD1(20).
DATA: INT_SPFLI TYPE STANDARD TABLE OF SPFLI WITH HEADER LINE.
SELECT DISTINCT CITYFROM FROM SPFLI INTO CORRESPONDING FIELDS OF TABLE INT_SPFLI.
START-OF-SELECTION.
  SET SCREEN 100.
MODULE PBO OUTPUT.
  LOOP AT INT_SPFLI.
    VALUE-KEY = INT_SPFLI-CITYFROM.
    APPEND VALUE.
  ENDLOOP.
   CALL FUNCTION 'VRM_SET_VALUES'
    EXPORTING
          ID     = 'DD1'
          VALUES = VALUE[].
ENDMODULE.
MODULE PAI INPUT.
  CASE SY-UCOMM.
    WHEN 'BTNEXIT'.
      LEAVE PROGRAM.
  ENDCASE.
ENDMODULE.