存储过程，select两个时间之内的问题

[cnidb]

if isDate(@beginTime)=1 and isDate(@endTime)=1
begin
set @inTmes=' and (order_Time BETWEEN '+cast(@beginTime As nvarchar(30))+' and '+cast(@endTime As nvarchar(30))+')'
end

在@beginTime @endTime以内明明有记录得到的结果却为空