I`ve got two language subdomains /de/ and /ru/

Selected answers from the Dumb SEO Questions Facebook & G+ community.

• 
  Rostyslav Chernyakhovskyy: Hi, I've asked a few days ago about a problem with subdomains.
  
  https://plus.google.com/u/0/+dopeless/posts/UegB1Hxiph7
  
  The problem is not solved, but I've discovered more problems )
  
  I've got two language subdomains /de/ and /ru/
  If I search google for site:www.dopeless-design(dot)de/ru/, everything looks ok.
  But if I search for ;site:www.dopeless-design(dot)de/de/, everything looks messed up. All (but one) titles and descriptions are wrong. All titles must have the same structure. I've changed them about a month ago, but it looks like some mess in google index. And the main page (site:www.dopeless-design(dot)de/de/) is missing. Looks, like Google doesn't index german version at all.
  
  there is a 301 redirect from www.dopeless-design(dot)de to www.dopeless-design(dot)de/de/ or /ru/
  
  If I search for ;site:www.dopeless-design(dot)de, there are some pages in index, that don't exist for more than a year. ;
  
  What can cause it? Thnx.
• 
  Bruce Chant: Have you tried using "href lang" attribute? This would avoid the need to perform a 301.
• 
  Bruce Chant: https://support.google.com/webmasters/answer/189077?hl=en
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  Rostyslav Chernyakhovskyy: +Bruce Chant hi, i currently use hreflang in sitemap, as it described here https://support.google.com/webmasters/answer/2620865