Cannot display enum values on kendo MVC grid?

See more:

MVC5

Kendo-UI

Enum

public class Voltage
  {
      public int Id{ get; set; }
      public string RefNo { get; set; }
      public VoltageLevel VoltageLevel { get; set; }

  }
  public enum VoltageLevel
  {
      LV = 1,
      MV = 2,
      HV = 3
  }

Controller

public ActionResult Voltage_Read([DataSourceRequest]DataSourceRequest request)
     {
         IQueryable<Voltage> voltage= db.Voltage;
         DataSourceResult result = voltage.ToDataSourceResult(request, voltage=> new {
             Id = voltage.Id,
             RefNo = voltage.RefNo,
             VoltageLevel = voltage.VoltageLevel,

         });

         return Json(result);
     }

View

@(Html.Kendo().Grid<entities.voltage>()
.Name("grid")
.Columns(columns =>
{
columns.Bound(c => c.RefNo);
columns.Bound(c => c.VoltageLevel); //here the voltagelevel didnt show.
})

What I have tried:

columns.Bound(c => c.VoltageLevel); //here the voltagelevel didnt show.