datepickers ontextchnaged event is not firing after selecting the date

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ASP.NET

jQuery

Hi ,

<script type="text/javascript">

    $(function () {
        $("#<%=txtReviewStartDate.ClientID%>").datepicker({
            changeMonth: true,
            changeYear: true,
            showButtonPanel: true,
            dateFormat: 'MM yy',
            onClose: function (dateText, inst) {
                var month = $("#ui-datepicker-div .ui-datepicker-month :selected").val();
                var year = $("#ui-datepicker-div .ui-datepicker-year :selected").val();
                $(this).datepicker('setDate', new Date(year, month, 1));
            }
        });
    });

    $(function () {
        $("#<%=txtReviewEndDate.ClientID%>").datepicker({
            changeMonth: true,
            changeYear: true,
            showButtonPanel: true,
            dateFormat: 'MM yy',
            onClose: function (dateText, inst) {
                var month = $("#ui-datepicker-div .ui-datepicker-month :selected").val();
                var year = $("#ui-datepicker-div .ui-datepicker-year :selected").val();
                $(this).datepicker('setDate', new Date(year, month, 1));
            }
        });
    });
</script>

<div class="form_lft_inner" runat="server" id="div7">
             <div class="TwoColumn_Form_Wrap_Lft">
                 Timescale
             </div>
             <div class="TwoColumn_Form_Wrap_Rht">

                 <asp:TextBox ID="txtReviewStartDate" AutoPostBack="true" OnTextChanged="txtReviewStartDate_TextChanged" runat="server" CssClass="graphinput"></asp:TextBox><img src="../../images/calander.png" style="margin: 0px 10px 0px 2px; float: left" />
                 <asp:TextBox ID="txtReviewEndDate"  runat="server" CssClass="graphinput"></asp:TextBox><img src="../../images/calander.png" style="margin: 0px 10px 0px 2px; float: left" />
             </div>

         </div>

in this my txtReviewStartDate_TextChanged event is not firing at all ..

Please suggest or correct me if i am wrong in this