not updating ztable

Hi experts,

Please help me.

following is my code to update ZTABLE.

LOOP AT t_coil INTO w_coil.

     SELECT SINGLE * FROM zstock

                     INTO w_stock

                     WHERE coilno = w_coil-coilno

                     AND slitid = w_coil-slitid.

     IF sy-subrc = 0.

       SELECT SINGLE * INTO w_lst FROM zcoilst WHERE coilno = w_coil-coilno

                      AND slitid = w_coil-slitid.

       IF w_lst-currpos <> '91'.

         UPDATE zcoilst SET currpos = '91'

                        WHERE coilno = w_coil-coilno

                        AND slitid = w_coil-slitid

                        and TIMES = w_lst-TIMES.

       ENDIF.

     ENDIF.

   ENDLOOP.

its working in Development but not in Quality.

help me.

thanks in advance

laxman.