Problem with Routine in Transformation

Question

I have a routine that uses TIMECALC_DIFF to determine the difference between to date/times held in timestamp format.
All it generates is a duration of zero, no matter what the inputs are.
Value for YDATTIM is 20050812121821 and for YDATTIMF  is 20050813121821 and the answer given is zero, when it should be 86400.
CONSTANTS:   gc_timezone_system      TYPE timezone    VALUE 'MSTNO'.
DATA:  t_first(14) TYPE c,
         t_last(14)  TYPE c,
         /BIC/YDATTIM TYPE timestamp,
         /BIC/YDATTIMF  TYPE timestamp,
         /BIC/YDATDUR TYPE i.
CALL FUNCTION 'TIMECALC_DIFF'
          EXPORTING
            timestamp1 = /BIC/YDATTIM
            timestamp2 = /BIC/YDATTIMF
            timezone   = gc_timezone_system
          IMPORTING
            difference = /BIC/YDATDUR.
     RESULT = /BIC/YDATDUR.
Thanks
Steve

Answer 1

In the transformation it generates the following code, and this doesn't seem to be editable;
  IMPORTING
    request     type rsrequest
    datapackid  type rsdatapid
    SOURCE_FIELDS-/BIC/YDATTIMF TYPE /BIC/OIYDATTIMF
    SOURCE_FIELDS-/BIC/YDATTIM TYPE /BIC/OIYDATTIM
   EXPORTING
     RESULT type tys_TG_1-/BIC/YDATDUR**
    DATA:
      MONITOR_REC    TYPE rsmonitor.
I have put all the code generated below
PROGRAM trans_routine.
      CLASS routine DEFINITION
CLASS lcl_transform DEFINITION.
  PUBLIC SECTION.
Attributs
    DATA:
      p_check_master_data_exist
            TYPE RSODSOCHECKONLY READ-ONLY,
*-    Instance for getting request runtime attributs;
    Available information: Refer to methods of
    interface 'if_rsbk_request_admintab_view'
      p_r_request
            TYPE REF TO if_rsbk_request_admintab_view READ-ONLY.
  PRIVATE SECTION.
    TYPE-POOLS: rsd, rstr.
  Rule specific types
    TYPES:
      BEGIN OF tys_SC_1,
     InfoObject: YDATTIMF Finish date/time.
        /BIC/YDATTIMF           TYPE /BIC/OIYDATTIMF,
     InfoObject: YDATTIM Start date/time.
        /BIC/YDATTIM           TYPE /BIC/OIYDATTIM,
     Field: RECORD.
        RECORD           TYPE RSARECORD,
      END   OF tys_SC_1.
    TYPES:
      BEGIN OF tys_TG_1,
     InfoObject: YDATDUR Duration.
        /BIC/YDATDUR           TYPE /BIC/OIYDATDUR,
      END   OF tys_TG_1.
$$ begin of global - insert your declaration only below this line  -
$$ end of global - insert your declaration only before this line   -
    METHODS
      compute_YDATDUR
        IMPORTING
          request                  type rsrequest
          datapackid               type rsdatapid
          SOURCE_FIELDS              type tys_SC_1
        EXPORTING
          RESULT                   type tys_TG_1-/BIC/YDATDUR
          monitor                  type rstr_ty_t_monitor
        RAISING
          cx_rsrout_abort
          cx_rsrout_skip_record
          cx_rsrout_skip_val.
    METHODS
      invert_YDATDUR
        IMPORTING
          i_th_fields_outbound         TYPE rstran_t_field_inv
          i_r_selset_outbound          TYPE REF TO cl_rsmds_set
          i_is_main_selection          TYPE rs_bool
          i_r_selset_outbound_complete TYPE REF TO cl_rsmds_set
          i_r_universe_inbound         TYPE REF TO cl_rsmds_universe
        CHANGING
          c_th_fields_inbound          TYPE rstran_t_field_inv
          c_r_selset_inbound           TYPE REF TO cl_rsmds_set
          c_exact                      TYPE rs_bool.
ENDCLASS.                    "routine DEFINITION
$$ begin of 2nd part global - insert your code only below this line  *
$$ end of 2nd part global - insert your code only before this line   *
      CLASS routine IMPLEMENTATION
CLASS lcl_transform IMPLEMENTATION.
  METHOD compute_YDATDUR.
  IMPORTING
    request     type rsrequest
    datapackid  type rsdatapid
    SOURCE_FIELDS-/BIC/YDATTIMF TYPE /BIC/OIYDATTIMF
    SOURCE_FIELDS-/BIC/YDATTIM TYPE /BIC/OIYDATTIM
   EXPORTING
     RESULT type tys_TG_1-/BIC/YDATDUR
    DATA:
      MONITOR_REC    TYPE rsmonitor.
$$ begin of routine - insert your code only below this line        -
CONSTANTS:   gc_timezone_system      TYPE timezone    VALUE 'GMTUK'.
DATA:  t_first(14) TYPE c,
         t_last(14)  TYPE c,
         /BIC/YDATTIM TYPE timestamp,
         /BIC/YDATTIMF  TYPE timestamp,
         /BIC/YDATDUR TYPE i.
CALL FUNCTION 'ZZTIMEDIFF'
          EXPORTING
            /BIC/YDATTIM = /BIC/YDATTIM
            /BIC/YDATTIMF = /BIC/YDATTIMF
            timezone   = gc_timezone_system
          IMPORTING
            difference = /BIC/YDATDUR.
     RESULT = /BIC/YDATDUR.
$$ end of routine - insert your code only before this line         -
  ENDMETHOD.                    "compute_YDATDUR
      Method invert_YDATDUR
      This subroutine needs to be implemented only for direct access
      (for better performance) and for the Report/Report Interface
      (drill through).
      The inverse routine should transform a projection and
      a selection for the target to a projection and a selection
      for the source, respectively.
      If the implementation remains empty all fields are filled and
      all values are selected.
  METHOD invert_YDATDUR.
$$ begin of inverse routine - insert your code only below this line-
... "insert your code here
$$ end of inverse routine - insert your code only before this line -
  ENDMETHOD.                    "invert_YDATDUR
ENDCLASS.                    "routine IMPLEMENTATION
Thanks
Steve