C#

private void loadWorker_DoWork(object sender, DoWorkEventArgs e)
{
    var sensors = AppCore.AppDAL.GetSensors();
    e.Result = sensors;
}

public List<SensorEntity> GetSensors()
{
    lock (lockObj)
    {
        var query = getSensorQuery();
        var results = query.OrderBy(x => x.SensorName).ToList();

<pre>
    // THIS CALLS GetSensorCategoryBELOW
    results.ForEach(x => x.Category = GetSensorCategory(x.SensorTypeID));

    return results;
}

public SensorCategoryEntity GetSensorCategory(long ID)
{
    var query = getSensorCategoryQuery();
    var results = query.Where(x => x.ID == ID).FirstOrDefault();  //<== FAILS HERE
    return results;
}

private IQueryable<SensorCategoryEntity> getSensorCategoryQuery()
{
    var query = (from sc in dataContext.SensorTypes
                    select new SensorCategoryEntity
                    {
                        ID = sc.ID,
                        Name = sc.Name
                    });

    return query;
}

private void loadWorker_DoWork(object sender, DoWorkEventArgs e)
{
    Thread.Sleep(500);

    var sensors = Falcon6Core.Falcon6DAL.GetSensors();
    e.Result = sensors;
}