title: linq query where int ID belongs to List<int>
body: <p>I'm having a problem with a linq query. I have used this similarly before but i cannot understand what could be wrong now.</p>
  
  <p><strong>Errors</strong></p>
  
  <blockquote>
    <p>The best overloaded method match for
    'System.Collections.Generic.List.Contains(int)'
    has some invalid arguments<br>
    Argument '1': cannot convert from 'int?' to 'int' ; refers to the where clause of rTestResults </p>
  </blockquote>
  
  <p><strong>Code:</strong></p>
  
  <pre><code>List&lt;int&gt; rMTCPlates = (from rP in mDataContext.Plates
                          where rP.SOItem.SONumberID == aSONumber
                          select rP.ID).ToList();
  
  var rTestResults = from rT in mDataContext.TestSamplesViews
                     where rMTCPlates.Contains(rT.PlateID)
                     select rT;  
  </code></pre>
  
  <p>Any idea whats going on?  </p>
  
  <p>Any help appreciated,<br>
  Thanks</p>