ALV summation in the output

Hai All,

When iam trying to sum on a particular coloumn in ALV output it is throwing a dump and uiam giving the part of the dump analysis.

assign component

<ls_fieldcat>-fieldname of structure rt_data to <g_field>.

if sy-subrc ne 0.

message x000(0k).

endif.

g_col_counter = g_col_counter + 1.

gs_lvc_data-row_pos = r_row_counter.

kindly suggest me where iam goin wrong or the possibility for the error.

Thanks & Regards,

Praveen.