Please see the code below:

```
[TestFixture]
    public class UnitTest1
    {
        [Test]
        public void TestMethod1()
        {
            DateTime dob = new DateTime(2001, 02, 29);
            DateTime todaysDate = new DateTime(2001, 02, 29);
        }
    }

```

When I run this code the second line of the method throws an exception: System.ArgumentOutOfRangeException: 'Year, Month, and Day parameters describe an un-representable DateTime.'. However, if I comment out the first line of the method it runs successfully. What is the problem?