Update Entity Date Column

I'm trying to update a column of type date using Entity object as below:

//Example 1
entity.SetColumnValue("BirthDate", "2001-09-15");
 
//Example 2
DateTime Date = DateTime.Parse("2001-09-15");
entity.SetColumnValue("BirthDate", Date );

The second example modifies the value successfully but when I open in client side the value doesn't show.