title: Problems with multiple selection screens
body: <p><code>START-OF-SELECTION</code> is not getting triggered in my program. I am trying to fetch book details based on book name and book author using multiple selection screens in ABAP. There are two pushbuttons and based on those selection screens are opened. When I click any of the push buttons, then selection screens are opened. But after I select entries from the dropdown list and click execute button, then the transaction goes to the initial screen with the pushbuttons. The book details are not displayed at all. <code>START-OF-SELECTION</code> is not triggered. Please help, I am a newbie in ABAP. Here is my program</p>
  
  <pre><code> REPORT y_multiple_screen.
  
      TABLES: sscrfields.
      TYPE-POOLS: vrm.
      DATA: param    TYPE vrm_id,
            values   TYPE vrm_values,
            wa_value LIKE LINE OF values.
  
  
  
      DATA: it_ybook TYPE TABLE OF ybook,
            wa_ybook TYPE ybook.
  
  
      FIELD-SYMBOLS: &lt;fs_book&gt; TYPE ybook.
  
  
      SELECTION-SCREEN BEGIN OF BLOCK blocker WITH FRAME TITLE text-001 NO INTERVALS.
      SELECTION-SCREEN SKIP.
      SELECTION-SCREEN BEGIN OF LINE.
      SELECTION-SCREEN PUSHBUTTON (30)  w_butn1 USER-COMMAND but1.
      SELECTION-SCREEN END OF LINE.
      SELECTION-SCREEN SKIP.
      SELECTION-SCREEN BEGIN OF LINE.
      SELECTION-SCREEN PUSHBUTTON (30)  w_butn2 USER-COMMAND but2.
      SELECTION-SCREEN END OF LINE.
      SELECTION-SCREEN SKIP.
  
      SELECTION-SCREEN END OF BLOCK blocker.
  
      SELECTION-SCREEN BEGIN OF SCREEN 1100.
      PARAMETERS: p_author TYPE char255 AS LISTBOX VISIBLE LENGTH 20.
  
  
      SELECTION-SCREEN END OF SCREEN 1100.
  
      SELECTION-SCREEN BEGIN OF SCREEN 1200.
  
      PARAMETERS: p_bname TYPE char255 AS LISTBOX VISIBLE LENGTH 20.
  
  
      SELECTION-SCREEN END OF SCREEN 1200.
  
      INITIALIZATION.
  
        w_butn1 = 'Search by author name'.
        w_butn2 = 'Search by book name'.
  
        "At selection-screen output.
  
      AT SELECTION-SCREEN.
        IF sscrfields-ucomm EQ 'BUT1'.
  
          CALL SELECTION-SCREEN 1100.
  
  
        ELSEIF sscrfields-ucomm EQ 'BUT2'.
  
          CALL SELECTION-SCREEN 1200.
        ENDIF.
  
      AT SELECTION-SCREEN OUTPUT.
  
        CLEAR it_ybook.
        SELECT *
        FROM ybook
        INTO TABLE it_ybook.
        CLEAR values.
        CLEAR wa_ybook.
        CLEAR wa_value.
        LOOP AT it_ybook INTO wa_ybook.
  
  
          wa_value-key = wa_ybook-book_author.
          wa_value-text = wa_ybook-book_author.
  
          APPEND  wa_value TO values.
          CLEAR wa_ybook.
          CLEAR wa_value.
        ENDLOOP.
  
  
  
        CLEAR it_ybook.
  
  
  
        CALL FUNCTION 'VRM_SET_VALUES'
          EXPORTING
            id              = 'P_AUTHOR'
            values          = values
          EXCEPTIONS
            id_illegal_name = 1
            OTHERS          = 2.
  
  
        CLEAR it_ybook.
        SELECT *
        FROM ybook
        INTO TABLE it_ybook.
  
        "CLEAR values.
        CLEAR wa_ybook.
        CLEAR wa_value.
  
        LOOP AT it_ybook INTO wa_ybook.
  
  
          wa_value-key = wa_ybook-book_name.
          wa_value-text = wa_ybook-book_name.
  
          APPEND  wa_value TO values.
          CLEAR wa_ybook.
          CLEAR wa_value.
        ENDLOOP.
  
  
  
        CLEAR it_ybook.
  
  
  
        CALL FUNCTION 'VRM_SET_VALUES'
          EXPORTING
            id              = 'P_BNAME'
            values          = values
          EXCEPTIONS
            id_illegal_name = 1
            OTHERS          = 2.
  
  
      START-OF-SELECTION.
          WRITE:/10 'Book ID',40 'Book Name',70 'Book Author',100 'Book Price'.
  
          CLEAR it_ybook.
          CLEAR wa_ybook.
          SELECT *
          FROM ybook
          INTO TABLE it_ybook
          WHERE book_name = p_bname.
          LOOP AT it_ybook INTO wa_ybook.
            WRITE:/10 wa_ybook-book_id,40 wa_ybook-book_name,70 wa_ybook-book_author,100 wa_ybook-book_price.
            CLEAR wa_ybook.
          ENDLOOP.
  
  
          WRITE:/10 'Book ID',40 'Book Name',70 'Book Author',100 'Book Price'.
  
          CLEAR it_ybook.
          CLEAR wa_ybook.
          SELECT *
          FROM ybook
          INTO TABLE it_ybook
          WHERE book_author = p_author.
          LOOP AT it_ybook INTO wa_ybook.
            WRITE:/10 wa_ybook-book_id,40 wa_ybook-book_name,70 wa_ybook-book_author,100 wa_ybook-book_price.
            CLEAR wa_ybook.
          ENDLOOP.
  </code></pre>