[求助]SQL存储过程莫名报错，求助

--此存储过程实现删除用户的全部数据，包括竞价排名数据、信息发布数据等等

create procedure delUser(
@userEmail varchar(100),
@result varchar(10) output
)
as
set nocount on
if @userEmail=null or userEmail=''
begin
set @result='参数传递错误，用户帐号丢失.'
return
end
else
begin
delete from [User8517,jjKeyWords,leaveMes,message] where( user8517.userEmail=@userEmail and jjKeyWords.jjKeyEmail=@userEmail and leaveMes.lMesEmail=@userEmail and message.MesEmail=@userEmail)
set @result='删除成功！'
end

为什么提示列明userEmail无效啊
怎么改啊