title: linq getting key from list keyvalue pair
body: <p>this is seems simple, but I have a list of keyvalue pairs  and a linq statement trying to get the the key, I dont understand why this dosent work Ex</p>
  
  <pre><code>   List&lt;KeyValuePair&lt;int, string&gt;&gt; list = new List&lt;KeyValuePair&lt;int, string&gt;&gt;();
  </code></pre>
  
  <p>list contains values: 1, test1 | 2, test2 | 3, test3 as data
  my linq statement is:</p>
  
  <pre><code>string Key = list.AsEnumerable(x =&gt; x.Value == "test2").Select(x =&gt; x.Key).ToString();
  </code></pre>
  
  <p>seems simple enough to work but dosent?</p>