ASP.Net AJAX-- how to display ajax response in html

Question

my code:

$(document).ready(function () {
$("[id*=Aspx_Dropdown_Back]").change(function () {
$.ajax({
type: "POST",
url: "View.aspx/GetVariables",
data:JSON.stringify({"xszBack": document.getElementById ( "<%= Aspx_Dropdown_Back.ClientID %>" ).value}),
contentType: "application/json; charset=utf-8",
dataType: "json",
success: OnSuccess,
failure: function() {
alert("F");
}
});
});
});
function OnSuccess(data) {
var msg = data.hasOwnProperty("d") ? data.d : data;
$("#divToAddTo").empty();
$("#divToAddTo").html(msg);
}

code behind:

[WebMethod, ScriptMethod(ResponseFormat = ResponseFormat.Json, UseHttpGet = false)]
public static string GetVariables(string xszBack)
{
string Retrunstring = "";
Retrunstring = "<asp:TextBox ID='TextBox31' runat='server' CssClass='TextBox_Text12' Width='250' />";
return zszRetrunstring;
}

im trying to get string(HTML string) from code behind function and display in DIV tag by using ajax reponse data.

 

but i cant do that.. no error raising..

 

if i given that HTML string directly in AJAX Success methos,, like below..

function OnSuccess(data) {
var $msg = data.hasOwnProperty("d") ? data.d : data;
$("#divToAddTo").empty();
//$("#divToAddTo").html($msg);
$("#divToAddTo").html('<asp:TextBox ID="TextBox11" runat="server" CssClass="TextBox_Text12" Width="250" /><br/><asp:TextBox ID="TextBox21" runat="server" CssClass="TextBox_Text12" Width="250" /><br/>');
}

its working fine... and two textbox's are generated inside DIV tag.

 

but the string, same string which i get from code behind.. its not working..

 

pls. dont refer any web reference... pls. give any code..

 

thanks all...