Error converting LINQ query with TimeSpan? to the list <>?

I am running the following LINQ to SQL query

var q =
    from O in db.GetTable<OptionsTraded>()
    where O.TradeDate.Date == dtpVolReport.Value.Date
    select new { O.TradeTime };

      

        
        
        
      

    

but when i try to convert this output to list:

var qq = q.ToList();

      

        
        
        
      

    

I am getting the error:

An unhandled exception of type 'System.InvalidCastException' occurred in System.Data.dll Additional Information: The specified order is not valid.

I only get this error when I select an attribute O.TradeTime

and it maps to a property with a type TimeSpan?

, which I'm sure is the route of the problem. If I try to select any other attribute in my table, include those mapped to other NULL types like int?

or double?

I don't get an error.

Has anyone encountered this before or can recommend what is the correct way to deal with TimeSpan?

?

This is how it is determined OptionsTraded

:

[Table(Name = "OptionsTraded")]
    public class OptionsTraded
    {
        private DateTime _TradeDate;
        [Column(Storage = "_TradeDate")]
        public DateTime TradeDate
        {
            get { return this._TradeDate; }
            set { this._TradeDate = value; }
        }

        private TimeSpan? _TradeTime;
        [Column(Storage = "_TradeTime")]
        public TimeSpan? TradeTime
        {
            get { return this._TradeTime; }
            set { this._TradeTime = value; }
        }
        .
        .
        .

      

        
        
        
      

    

And in SQL-Server:

I've also tried:

public class TradeViewModel
{
    public TimeSpan? TradeTime { get; set; }
}

var q =
    from O in db.GetTable<OptionsTraded>()
    where O.TradeDate.Date == dtpVolReport.Value.Date
    select new TradeViewModel {TradeTime = O.TradeTime};

var qq = q.ToList();

      

        
        
        
      

    

but i am getting the same error yet