How to assign value to DateTime? field of object.

Question

I have declared Person class as below.

 

public class Person

{

public string Prefix { get; set; }

public string FirstName { get; set; }

public string LastName { get; set; }

public DateTime? DateOfBirth { get; set; }

}

 

I create an Person object.

 

Person _person = new Person { Prefix = "Mr", FirstName = "William", LastName = "Jonathan", DateOfBirth = DateTime.Now.AddYears(-29) }; 

 

Problem --> I got an error "Object reference not set to an instance of an object." in setting value to DateOfBirth.

 

Anybody help me? How to solved it?

 

Thank you.

Thakerng.