Error In Calling a screen from ALV Display

Hello Experts,

I have the following requirement,

I have to display the report using    'REUSE_ALV_GRID_DISPLAY'. After displaying the ALV , the ALV screen must have a button say 'B1', which i have done by creating a GUI. In ALV the fisrt column is a checkbox column, so whenever i select few rows by selecting the check box and click on that button it lead to new screen on which few messages will be written. For this i have created a form and gave that form in the FM as below,

  i_callback_user_command  = 'f_Form1'.

I have also created a new screen.

My Problem is whenever i select a checkbox and click on the button it is leadin to the new screen and even the title is getting displayed,but my messages that i write there are not getting displayed, furthur the function key in the screen used for back is also not working. I have coded the form as below,

   FORM f_Form1 USING p_ucomm TYPE sy-ucomm rs_selfield TYPE slis_selfield.

  CASE p_ucomm.
    WHEN 'B1'.
      DATA ref TYPE REF TO cl_gui_alv_grid.

      CALL FUNCTION 'GET_GLOBALS_FROM_SLVC_FULLSCR'
        IMPORTING
          e_grid = ref.

      CALL METHOD ref->check_changed_data.

      LOOP AT gt_output INTO wa_output WHERE chkbox = 'X'.
        MOVE-CORRESPONDING wa_output TO wa_create.
        APPEND wa_create TO gt_create.
      ENDLOOP.

      IF gt_create IS NOT INITIAL.

        CALL FUNCTION 'FM TO CREATE ORDER'   ---> This is a customized FM to create order which is working fine
          TABLES
            t_flthdr = gt_create.

        SET SCREEN 9001.
        CALL SCREEN 9001.

        LOOP AT gt_create INTO wa_create.
          IF  wa_create-zfltcd IS INITIAL.
            WRITE: /'Creation  is successful for order no:', wa_create-ZSRORD.
          ELSEIF wa_create-zfltcd IS NOT INITIAL.
            WRITE: /'Creation of is not successful'.
          ENDIF.
        ENDLOOP.

      ELSEIF gt_create IS INITIAL.
        MESSAGE e018(xxx) DISPLAY LIKE 'I'. --> This message will indicate to select a checkbox if user has not selected any.
      ENDIF.

  ENDCASE.

ENDFORM.

And in the PAI of the screen i have coded like this,Even this  function key is also not working, I want the screen to leave to the previous page.

    CASE sy-ucomm.
    WHEN 'FC_BACK'.
      LEAVE SCREEN.
  ENDCASE.

Can you please guide me in rectifying these issues. Your immediate response is highly appreciated and am very thankful to you

Thanks and regards,

Satish Kumar Balasubramanian.