title: Lookup Field in LINQ to Sharepoint sometimes doesnt get retrieved
body: <p>Im trying to use a LINQ to SharePoint to retrieve and filter a simple list with lookup field</p>
  
  <pre><code>  var list = _db.Leaves.Where(x =&gt;x.Employee != null &amp;&amp; x.Employee.Id == empId).ToList();
  </code></pre>
  
  <p>problem is sometimes randomly the Field Employee is null ! i dont know why ! its so strange that it happens randomly which cause it to throw casting exception, any one know why this is happening ?</p>
  
  <pre><code>&lt;Field Type="Lookup" DisplayName="Employee" Required="True" EnforceUniqueValues="FALSE" List="Lists/Employees" ShowField="EnFullName" ID="{26183411-9bbf-48a1-b2f8-3388b98c7fef}" Name="Employee" ColName="int2" RowOrdinal="0" Indexed="TRUE" RelationshipDeleteBehavior="Restrict" /&gt;
  </code></pre>