Why doesn't Scrapy Xpath parse some expressions?

Question

XPath

Good afternoon!
I'm trying to learn Scrapy by adapting the found workable example to my needs.

#! coding: utf-8
__author__ = 'acman'
from scrapy.contrib.spiders import CrawlSpider, Rule
from scrapy.contrib.linkextractors import LinkExtractor
from scrapy.item import Item, Field
from scrapy.contrib.loader import XPathItemLoader
from scrapy.contrib.loader.processor import TakeFirst
from scrapy.selector import HtmlXPathSelector
#
#
class ScrapyTestItem(Item):
    title = Field()
    imagelink = Field()
    url = Field()
    price = Field()
    field_11 = Field()

class Test03Loader(XPathItemLoader):
    default_output_processor = TakeFirst()    
  
class ScrapyTestSpider(CrawlSpider):
    name = "test03"
    allowed_domains = ["pastelmebel.ru"]
    start_urls = ["http://pastelmebel.ru/shop/bedroom-furniture/bedroom-august/the-cabinet-wall-s-83-sfw1w-august-wenge/"]

    rules = (
        Rule(LinkExtractor(allow=('/bedroom-august/')), 
            callback='parse_item', follow=True),
    )

    def parse_item(self, response):
        hxs = HtmlXPathSelector(response)
        l = Test03Loader(ScrapyTestItem(), hxs)

        l.add_xpath('title', "//h1[last()]/text()")
        l.add_xpath('imagelink', "//img[1]/@src")
        l.add_xpath('price', "//*[@class='itemOtherPricePrice number']/text()")  
        l.add_xpath('field_11', ".//*[@id='tab-sub-about-features']/table/tbody/tr[1]/td[2]/span") 
        l.add_value('url', response.url)

        return l.load_item()

So, the field_11 field does not get into the final output, the rest (title, price, image path) are parsed normally.
I took the expression for Xpath from FirePath - everything is fine there, valid.
What else can be?

Answer 1

and you yourself, excuse me, understand what is written there? )
.// this one how?
also *
try to learn how to write XPath expressions (a hint is when they don’t have such [1] [2]) and working with XPath will become easy and understandable

Answer 2

delete /tbody/
you can test expressions in scrapy slell
for example
scrapy shell http://targetsite.com