problem in Date Time Picker in C#

Question

hello every one ,

i have problem in date time picker actually i m putting validation for cheque date .. it should not be greater than 180 days . because cheque id valid for 180 days so user only can put date from today dates to 180 days .. is it pssoible in c#.. if yes than let me know.. this is my code please check it ....

if (dtp_cheque_date.Value < DateTime.Today)

            {

                MessageBox.Show("Cheque Date cannot be less than today!");

                dtp_cheque_date.Value = DateTime.Today;

            }

thanks in Advance