Reuse_ALV_Grid_Display not generating spool in background

Dear Experts,

Urgent help required.

Reuse_ALV_Grid_Display is not generating any spool when Iam running my custom report in background.

Please help.

Please find FM call for the same.

CALL FUNCTION 'REUSE_ALV_GRID_DISPLAY'
         EXPORTING
           i_callback_program      = SY-REPID
           i_callback_top_of_page  = 'TOP-OF-PAGE'  "see FORM
           i_callback_user_command = 'USER_COMMAND'
           is_layout               = gs_layout
           it_fieldcat             = gt_fcat
           i_save                  = 'A'
           is_variant              = gs_variant
*         is_print               = wa_print
         TABLES
           t_outtab                = gt_list.