title: At least one object must implement IComparable calling OrderBy()
body: <p>I already saw this question, but i didn't find my happiness with the answers...</p>
  
  <p>I'm trying to do that: </p>
  
  <pre><code>var coll = JsonConvert.DeserializeObject&lt;ObservableCollection&lt;ArticleJSON&gt;&gt;(json);
  coll = coll.OrderBy(a =&gt; a.tags).Distinct().ToList();
  </code></pre>
  
  <p>Throws an error:</p>
  
  <blockquote>
    <p>At least one object must implement IComparable.</p>
  </blockquote>
  
  <p>For the moment i didn't find the solution so i did that:</p>
  
  <pre><code>List&lt;string&gt; categories = new List&lt;string&gt;();    
  var coll = JsonConvert.DeserializeObject&lt;ObservableCollection&lt;ArticleJSON&gt;&gt;(json);
  
  for (int i = 0; i &lt; test.Count; ++i)
  {
      for (int j = 0; j &lt; test[i].tags.Count; ++j)
      {
          _categories.Add(test[i].tags[j]);
      }
  }
  
  categories = _categories.Distinct().ToList();
  </code></pre>
  
  <p>It works but i'm curious to know why the first one don't work.</p>
  
  <p>EDIT : </p>
  
  <p>My data come from a JSON : </p>
  
  <pre><code>            'tags': [ 
  
                                          'Pantoufle',
                                          'Patate'
                                       ]
                              },
              public List&lt;string&gt; tags { get; set; }
  </code></pre>