imobsuz

((@BasicDatePicker1 is null) or
       (@BasicDatePicker2 is null) or
       ((Date1 >= @BasicDatePicker1) and
        (Date2 <= @BasicDatePicker2)))

a basicdatepicker is just a textbox that had a date, however 

@BasicDatePicker is null is not allowed in .NET (date must be <9999 and >1750)