field symbol

Hi...am assigning a mixed structure (contains both char & int or packed) to a field symbol and then to a variable . But it is throwing dump........can anyone suggest a solution to this...

DATA: BEGIN OF I_DATA OCCURS 0,

V_WA(820) TYPE C,

END OF I_DATA.

DATA: V_COUNT TYPE I.

DATA: BEGIN OF I_JOB OCCURS 0,

LIST LIKE TBTCJOB, "len = 476

V_SEL(01) TYPE C,

END OF I_JOB.

*********

DO.

ADD 1 TO V_COUNT.

ASSIGN COMPONENT V_COUNT OF STRUCTURE I_JOB TO <F>.

IF SY-SUBRC NE 0.

EXIT.

ENDIF.

MOVE <F> TO I_DATA-V_WA.

APPEND I_DATA.

ENDDO.

Thanks

Rgds