title: Why I can't access the "item2.UserName"
body: <p>This is the right 
  <img src="https://i.stack.imgur.com/V5PQ2.jpg" alt="enter image description here">
  This is the error
  <img src="https://i.stack.imgur.com/0p5Ib.jpg" alt="enter image description here"></p>
  
  <pre><code>from item1 in EL_Course_Courses join item2 in Users on item1.Speaker equals item2.Id into temps 
  
  from item3 in temps group item3 by item1.Name into g 
  
  //from item3 in temps group item3 by item2.UserName into g 
  
  select new {g.Key, Amount=g.Count()}
  </code></pre>
  
  <p>I want to know why I can't group by "item2.UserName"</p>