Use of ALV To Calculate TOTAL of a particular field and setting the the total text by the layout property

REPORT  ZAVI_FEVER2.

TYPE-POOLS: SLIS.

DATA: IT_SPFLI TYPE TABLE OF SPFLI,
      WA_SPFLI TYPE SPFLI.
DATA: IT_FCAT TYPE  SLIS_T_FIELDCAT_ALV,
      WA_FCAT TYPE  SLIS_FIELDCAT_ALV.

DATA: WA_LAYOUT TYPE SLIS_LAYOUT_ALV.
SELECT * FROM SPFLI INTO TABLE IT_SPFLI .



  CALL FUNCTION 'REUSE_ALV_FIELDCATALOG_MERGE'
   EXPORTING
     I_PROGRAM_NAME               = 'SY-REPID'
*     I_INTERNAL_TABNAME           =
     I_STRUCTURE_NAME             = 'SPFLI'
*     I_CLIENT_NEVER_DISPLAY       = 'X'
*     I_INCLNAME                   =
*     I_BYPASSING_BUFFER           =
*     I_BUFFER_ACTIVE              =
    CHANGING
      ct_fieldcat                  = IT_FCAT
   EXCEPTIONS
     INCONSISTENT_INTERFACE       = 1
     PROGRAM_ERROR                = 2
     OTHERS                       = 3
            .
  IF sy-subrc <> 0.
* Implement suitable error handling here
  ENDIF.


LOOP AT IT_FCAT INTO WA_FCAT.
  IF WA_FCAT-FIELDNAME = 'DISTANCE'.
    WA_FCAT-DO_SUM = 'X'.
    MODIFY IT_FCAT FROM WA_FCAT TRANSPORTING DO_SUM.
    ENDIF.
    ENDLOOP.

    WA_LAYOUT-TOTALS_TEXT = 'TOTAL'.

 CALL FUNCTION 'REUSE_ALV_LIST_DISPLAY'
  EXPORTING
*    I_INTERFACE_CHECK              = ' '
*    I_BYPASSING_BUFFER             =
*    I_BUFFER_ACTIVE                = ' '
    I_CALLBACK_PROGRAM             = 'SY-REPID'
*    I_CALLBACK_PF_STATUS_SET       = ' '
*    I_CALLBACK_USER_COMMAND        = ' '
    I_STRUCTURE_NAME               = 'SPFLI'
    IS_LAYOUT                      = WA_LAYOUT
    IT_FIELDCAT                    = IT_FCAT
*    IT_EXCLUDING                   =
*    IT_SPECIAL_GROUPS              =
*    IT_SORT                        =
*    IT_FILTER                      =
*    IS_SEL_HIDE                    =
*    I_DEFAULT                      = 'X'
*    I_SAVE                         = ' '
*    IS_VARIANT                     =
*    IT_EVENTS                      =
*    IT_EVENT_EXIT                  =
*    IS_PRINT                       =
*    IS_REPREP_ID                   =
*    I_SCREEN_START_COLUMN          = 0
*    I_SCREEN_START_LINE            = 0
*    I_SCREEN_END_COLUMN            = 0
*    I_SCREEN_END_LINE              = 0
*    IR_SALV_LIST_ADAPTER           =
*    IT_EXCEPT_QINFO                =
*    I_SUPPRESS_EMPTY_DATA          = ABAP_FALSE
*  IMPORTING
*    E_EXIT_CAUSED_BY_CALLER        =
*    ES_EXIT_CAUSED_BY_USER         =
   TABLES
     t_outtab                       = IT_SPFLI
  EXCEPTIONS
    PROGRAM_ERROR                  = 1
    OTHERS                         = 2
           .
 IF sy-subrc <> 0.
* Implement suitable error handling here
 ENDIF.