Button to Save and Add New

I am using Visual Studio 2010 and Visual Basic to design a web form.  I have a button on my web form that saves my data to my SQL database (this works), and then I want it to clear out some of the fields on the form so I can add a new request.  Some of the fields are cleared out - the date fields are not.  The fields are filled with a "1", not matter if I set it to = vbNull or I set it to "".  Here is my code.  I appreciate any help you can give me!
DropDownList1.Text = vbNull TextBox2.Text = vbNull TextBox1.Text = vbNull CheckBox1.Checked = False 'These are the 2 fields that are giving me a "1" instead of a blank or cleared field. DropDownList3.Text = "" DropDownList2.Text = vbNull