John is correct. It is your problem don't know how to use
See that function accepts a format.
DateTimeFormatInfo info = new DateTimeFormatInfo();
info.ShortDatePattern = "dd/MM/yyyy";
DateTime.TryParse("30/3/2011", info, DateTimeStyles.None, out dob);
This way it works. You are ready to search what tryparse doing, instead you are simply looking for ready answer. Better try something.