<select> tag is removed from design by Binding dropdownlist

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jQuery

VS2013

I am Binding dropdownlist.
My code is

<asp:UpdatePanel ID="upd1" runat="server" >
            <ContentTemplate> <div class="col-md-3">
                            
                                <asp:Label runat="server" ID="lblAllocationOrderNo" Text="Allocation Order No."></asp:Label>
                            

                            <asp:DropDownList runat="server" ID="ddlAllocationOrderNo" CssClass="form-control input-sm">
                            </asp:DropDownList>


                         
                            <asp:RequiredFieldValidator ID="rfvAllocationOrderNo" runat="server" ControlToValidate="ddlAllocationOrderNo"
                                ValidationGroup="frmSelection"
                                ErrorMessage="Allocation No. Required" CssClass="fa text-red" SetFocusOnError="True" Display="Dynamic"
                                InitialValue="0">
                            
                            </asp:RequiredFieldValidator>


                        </div>

            </ContentTemplate>
        </asp:UpdatePanel>

Before Binding it source code is

<select id="ContentPlaceHolder1_ddlAllocationOrderNo"></select>

there is no option
after Binding by given code
<pre lang="Javascript">

function getAllocationOrderN() {

try {


var fromdate = $('#<%=txtFromDate.ClientID%>').val();
var todate = $('#<%=txtToDate.ClientID%>').val();
var DFSO = $('#ContentPlaceHolder1_ddlDFSO :selected').val();


if (DFSO != '' & fromdate != '' & todate != '') {


$.ajax(
{
type: "POST",
contentType: "application/json; charset=utf-8",
url: "../scm/Search_CS.ashx?act=falloc&DFSO=" + DFSO + "&fromdate=" + fromdate + "&todate=" + todate,
data: "{}",
dataType: "json",
async: true,
selector: '#<%=ddlAllocationOrderNo.ClientID %>'
,
success: function (data) {


$("[id*=ddlAllocationOrderNo]").empty();
for (var i = 0; i < data.length; i++) {


$("[id*=ddlAllocationOrderNo]").append($("&lt;option>&lt;/option>").val(data[i].AllocValue).html(data[i].AllocationOrderNo));
}

}
});

}
else {
$("select[id$=ddlAllocationOrderNo] > option").remove();
}
}
catch (e) {

}

}</pre>

source code is

<option value="0">Select One</option>
<option value="1">123456</option>

select tag is not there.