I read in the "inside c#" book that exists diferences between the types.
the help also said that a struct(DateTime is a Struct) is a value type  so, it
can´t be null.

a reference can be null so i know when it exists or not

My problem is know when this DateTime has been initializaed or not.

In this case I can´t cast my textbox to DateTime format because i have one
textbox for each part of the date (day,month,year,hour,minute).