用scrapy爬了图书馆书籍的书名和评论，用Chrome的检查拔下来的Xpath，但是运行爬虫返回的是空元素，请问各位哪里出了问题，谢谢大家。
截图：

附上我的Scrapy源码，请大家多指教，谢谢！

from scrapy import Spider
from scrapy.selector import Selector
from CommentCrawl.items import CommentcrawlItem

class commentcrawl(Spider):
    name = "commentcrawl"
    allowed_domains = ["http://opac.lib.bnu.edu.cn:8080"]
    start_urls = [
        "http://opac.lib.bnu.edu.cn:8080/F/S9Q2QIQV5D9R9HBHPI2KNN8JH11TRIRSIEPKYQLTAQQ17LA6B6-16834?func=full-set-set&set_number=010408&set_entry=000001&format=999",
    ]
    def parse(self,response):
        item = CommentcrawlItem()
        item['name'] = Selector(response).xpath('//*[@id="details2"]/table/tbody/tr[1]/td[2]/a/text()').extract()
        item['comment'] = Selector(response).xpath('//*[@id="localreview"]/text()').extract()
        yield item