convert code form C# 2008 to C# 2005 have DataClass ?

I ask you to help me transfer code below into C#2008 to C#2005 ?, which takes the form type class DataClass.cs
[CODE]
//Example 1:
public static implicit operator DataClass(double? othaNumba)
        {
            return new DataClass() //error this place
            {
                DoubleValue = othaNumba == null ? null : (double?)Convert.ToDouble(othaNumba) // error this place
            };
        }
[/CODE]