title: Argument type is not assignable to parameter type
body: <p>I have such code:</p>
  
  <pre><code>List&lt;Pair&lt;string, string&gt;&gt; docs = new List&lt;Pair&lt;string, string&gt;&gt;(); 
  iErr = ftpconnect.ListAllDocuments(docs, build.BuildId.ToString());
  </code></pre>
  
  <p>Interface prototype of ListAllDocuments is:</p>
  
  <pre><code>Int32 ListAllDocuments(List&lt;Pair&lt;string, string&gt;&gt; DocList, string Path);
  </code></pre>
  
  <p>And I get an error</p>
  
  <blockquote>
    <p>Error   21:    The best overloaded method match for 'OperatorPanelWrapper.FtpTransportLibWrapper.ListAllDocuments(System.Collections.Generic.List&lt;OperatorPanel.Pair&lt;string,string>>, string)' has some invalid arguments</p>
  </blockquote>
  
  <p>Why do I get this error?</p>