Set A fixed date in Ajax Calendar Extender in asp.net using javascript

//HTML

<asp:TextBox runat="server" Width="105px" ID="TextBox1" ></asp:TextBox>

 <asp:CalendarExtender ID="CalendarExtender1" runat="server" PopupButtonID="dt_From"

                                    TargetControlID="dt_From" Enabled="True" Format="dd/MM/yyyy" BehaviorID="startdate"</asp:CalendarExtender>

<asp:TextBox runat="server" Width="105px" ID="TextBox2" ></asp:TextBox>

<asp:CalendarExtender ID="CalendarExtender2" runat="server" PopupButtonID="dt_To"

  BehaviorID="enddate" TargetControlID="dt_To" Enabled="True" Format="dd/MM/yyyy">

                                </asp:CalendarExtender>

//Script

<script>

function setdate() {

                    var dsd = new Date(2014, 03, 01); //fixed date

                    //start date of calender

                    dsd.setDate(dsd.getDate() + 1);   // add one day in fixed date

                    dsd.setDate(dsd.getDate() - 1);   // subtract one day in fixed date

                    //end date of calender control

                    var ded = new Date(2015, 02, 31);

                    ded.setDate(ded.getDate() + 1);

                    //CalendartxtBenFromb is behaviour id of the calender control

                    $find("startdate").set_startDate(dsd);

                    $find("enddate").set_startDate(dsd);

                    return false;

                }

</script>

//result