Linq MAX returns null on DateTime Type

Hi

System.Nullable<DateTime> DateToSelect = (from p in db.Archived select p.TestDate).Max();

I'm trign to return a date from a table but if there are no records in the table i get the Error

The null value cannot be assigned to a member with type System.DateTime which is a non-nullable value type.

How do i stop this null error if there are no records matching the criteria

I also have the problem when there are records in the table and i place a where statement in the LINQ i get the same error even if there are records that meet the criteria.

e.g.
System.Nullable<DateTime> WinningDateToSelect = (from p in db.qtxt_Competitions_Archived_Winners where p.ID = 1 select p.WinningDate).Max();