ALV report with internal in field symbol

Question

Hi Shifu ABAP,
I have ALV report.
My problem is when I tried to do sum using the sum icon. I got a message 'desired operation cannot be performed for column 'Dignostic delay'. Is it because I used field symbol, then when I clicked on the column it didn't recorgnise the field.
FYI.
1)The internal table for my ALV report is stored in field symbol.
2)I dont have a problem to display the report.
3)I had to set 'do_sum' at ALV field category, still doesn't work
My source code to define ALV category.
loop at i_qpcd into wa_qpcd.
CLEAR ls_fieldcat2.
ls_fieldcat2-col_pos = pos2.
ls_fieldcat2-fieldname = wa_qpcd-code.
ls_fieldcat2-reptext_ddic = wa_qpcd-desc.
ls_fieldcat2-just = 'C'.
ls_fieldcat2-do_sum = 'X'.
APPEND ls_fieldcat2 TO gt_fieldcat2.
endloop.
My source code call the ALV FM
CALL FUNCTION 'REUSE_ALV_GRID_DISPLAY'
EXPORTING
     i_callback_program         = 'ZMPMR001_Q1OOT'
     i_callback_pf_status_set = 'PF_STATUS_SET'
     is_layout                        = ls_layout
     it_fieldcat                       = gt_fieldcat2[]
     is_print                          = ls_print
TABLES
     t_outtab                         = <l_table>
EXCEPTIONS
     program_error                 = 1
OTHERS = 2.
IF sy-subrc <> 0.
MESSAGE ID sy-msgid TYPE sy-msgty NUMBER sy-msgno
WITH sy-msgv1 sy-msgv2 sy-msgv3 sy-msgv4.
ENDIF.
Thanks a lot in advance for your attention.

Answer 1

my situation is like this, declare the internal tble
1) data : begin of itab occurs 0,          
            code like qpcd-code,
            desc like QPCT-KURZTEXT,
          end of itab.
2) populate the itab like this
code           desc
01              desc 1
02              desc 2
03              desc 3
3) take the selected record converted it into new dynamic internal table using field symbol declare as table, now the component of this new table are 01, 02 and 03.
4) populate the new table with some data, so technically my new table structure will be like this
01         02         03
1           0          1
0           0          3
2           2          2
5) display the new table in ALV report, in ALV I tried to sum-up each of column.
6) Question : HOW can I convert the componet 01, 02 and 03 as an integer/numeric field.
Regards
Nislina