问RIA DomainService + ActiveRecord

EN

public IEnumerable<SE_NorthWind.SuperEmployee> GetIntegers()
{
  return SE_NorthWind.SuperEmployee.All()
    .Where(emp => emp.Issues > 100)
    .OrderBy(emp => emp.EmployeeID);
}

Error   7   Entity 'SE_NorthWind.SuperEmployee' has a property 'Columns' with an unsupported type.  SuperEmployee

Error   4   The entity 'SE_NorthWind.SuperEmployee' does not have a key defined. Entities exposed by DomainService operations must have must have at least one property marked with the KeyAttribute.   SuperEmployee

...
Columns.Add(new DatabaseColumn("EmployeeID", this)
            {
                IsPrimaryKey = true,
                DataType = DbType.Int32,
                IsNullable = false,
                AutoIncrement = true,
                IsForeignKey = false,
                MaxLength = 0
            });
...