title: Scrapy Spider returns None instead of Item
body: <p><strong>I've found the answer, down below. In short, wrong Indentation in the ItemPipeline caused it to return None.</strong></p>
  
  <p>I've been trying to write a CrawlSpider in Scrapy, having never worked with python before. The Spider crawls,calls the callback function, extracts data and fills the item, but it always returns None. I've tested it with a print article call, everything was in order. I have tried this both with yield and return ( though I still don't understand the difference). Frankly, I'm out of ideas. Down below is the callback function.//edit added the spider code as well</p>
  
  <pre><code>class ZeitSpider(CrawlSpider):
  name= xxxx
  allowed_domains = ['example.com']
  start_urls = ['http://www.example.com/%d/%d' %(JAHR,39)]
  rules = (Rule(SgmlLinkExtractor(restrict_xpaths=('//ul[@class="teaserlist"]/li[@class="archiveteaser"]/h4[@class="title"]')),callback='parse_url',follow=True),)
  
  
      def parse_url(self,response):
          hxs = HtmlXPathSelector(response)
  
          article = Article()
  
          article['url']= response.url.encode('UTF-8',errors='strict')
  
          article['author']= hxs.select('//div[@id="informatives"]/ul[@class="tools"]/li[@class="author first"]/text()').extract().pop().encode('UTF-8',errors='strict')
          article['title']= hxs.select('//div[@class="articleheader"]/h1/span[@class="title"]/text()').extract().pop().encode('UTF-8',errors='strict')
  
          article['text']= hxs.select('//div[@id="main"]/p/text()').extract().pop().encode('UTF-8',errors='strict')
  
          article['excerpt'] = hxs.select('//p[@class="excerpt"]/text()').extract().pop().encode('UTF-8',errors='strict')
          yield article
  </code></pre>
  
  <p>and the item definition</p>
  
  <pre><code>class Article(Item):
      url=Field()
      author=Field()
      text=Field()
      title=Field()
      excerpt=Field()
  </code></pre>