how to display condition applied message to datetimepicker

Question

hi friends,
        i am doing application for leave approval in my SAVE button i have wrote code like this

 if (dtpToDate.Text =="")
            {
                errorMsg("Please Enter The todate");
                dtpToDate.Focus();
            }
when i click save button without selecting todate it have show message please enter the todate but the current date is aromatically storing in date base because when i run the application the current date is displaying in datetimepicker so when i click my save button date is storing. How i can i show message .
could anyone help me

thanks