Formatting a string with Date/time picker parsing

I am trying to format a string to a list box with date input from a date/time picker and can't figure out how to parse it to do this. So far I have:

Dim Customer As String
Dim Video As String
Dim DueDate As Object
Dim Fee As Double
Dim fmtstr As String = "{0, -20}{1, 6}{2, 12}{3, 12}"
lstRentals.Items.Add(String.Format(fmtstr, Customer, Video, DueDate))

Any help would be appreciated!