title: "Object mapping could not be found for Type with identity" Exception
body: <p>I use EF 4.1 with POCO. 
  Entities with edmx are located in a separate assembly.</p>
  
  <p>When I call: </p>
  
  <pre><code>var key = new EntityKey("MyEntities.Vendors", "Id", vendorId);
  if (ctx.TryGetObjectByKey(key, out vendor)) ...
  </code></pre>
  
  <p>Exception is thrown "Object mapping could not be found for Type with identity"</p>
  
  <p>As far as I understand EF looks for Vendor in the calling assembly and can not find it there.
  So it should be the way of telling the context where to search types, but I have no idea which one.</p>