title: EntityDateSource must implement IQueryableDataSource?
body: <p>I'm trying to use a QueryExtender control in ASP.NET to provide search on a GridView. I'm using an EntityDataSource, but when I wire everything up and run the code I get an error that:</p>
  
  <blockquote>
    <p>DataSource 'EntityDateSource1' must implement IQueryableDataSource.</p>
  </blockquote>
  
  <p>How do I "implement" IQueryableDataSource? I'm running ASP.NET 4.0.</p>