问个问题

select pro_id,pro_name,pro_spec,pro_city,sum(psl_qty),sum(psl_qty)*(psl_prc2-psl_prc1) as '让利金额'
from pos.p_sale inner join pos.product on pro_id = psl_pro_id
where psl_br_id = '0104' and
         psl_prc1 <> psl_prc2 and
         psl_date between '2007/01/01' and '2007/02/10'
         group by pro_id,pro_name,pro_spec,pro_city;


这个语句有什么错误？