title: The object cannot be deleted because it was not found in the object state manager
body: <p>Im currently using Jtable to handle a list of eventtypes, but everytime I try to delete via the table I get the error "Value cannot be null. parameter name: entity".</p>
  
  <pre><code>    [HttpPost]
      public JsonResult DeleteEventType(EventType eventType)
      {
          using (var db = new ICTTBEntities())
          {
              try
              {
                  var newObj = db.EventTypes.SingleOrDefault(e =&gt; e.EventTypeID == eventType.EventTypeID);
                  if (newObj != null)
                  {
                      db.EventTypes.Remove(newObj);
                      db.SaveChanges();
                      return Json(new { Result = "OK" });
                  }
                  return Json(new { Result = "ERROR", Message = "eventType is null" });
              }
              catch (Exception ex)
              {
                  return Json(new { Result = "ERROR", Message = ex.Message });
              }
          }
      }
  </code></pre>
  
  <p>Any advice?</p>