title: How do I add modelstate error to a list
body: <p>I have a view that uses a list of modelitems like this: </p>
  
  <pre><code>List&lt;It4You.AlertBrick.Library.Domain.Order.AbOrderLineItemPicked&gt;
  </code></pre>
  
  <p>When I get this list serverside I check if this is one type of item, it has to have a valid serial number. If its another type I check if the user has put a checkmark in the "picked" checkbox. If both of these fails, I would like to add a modelstate error to this row. What is the best way of doing this? </p>