Having a problem with Datepicker -

Having a problem with Datepicker -

Hello, I have a website that is using the datepicker control.  The problem I am having is that sometimes (like 1 in 50) if a date is put into a textbox, and then you click back into that textbox to delete the date, it won't work.  You need to click inside the textbox a second time in order to be able to delete the text inside the textbox.  What can possibly be done to remedy this?  Here is how it is implemented:

    <script language="javascript" type="text/javascript" src="../../Scripts/jquery-1.9.1.js"></script>
    <script language="javascript" type="text/javascript" src="../../Scripts/jquery-ui-1.10.3.custom.js"></script>
    <script type="text/javascript">

        $(document).ready(function () {
            $('.calendarTextBox').datepicker({
                changeYear: true,
                changeMonth: true,
                minDate: new Date(1999, 9, 1),
                maxDate: new Date(2040, 8, 30),
                yearRange: "c-50:c+50",
                closeText: "Close",
                showButtonPanel: true
            });
        });
</script>

<asp:TextBox ID="tbCreatedAfter" runat="server" Width="75px" CssClass="calendarTextBox"></asp:TextBox>