jquery 绑定的事件触发不了，求指教
jQuery 代码：
$(document).ready(function(){
  $("#tbUserName").bind("change",function(){
  $.ajax({
  type:"Get",
  url:"/AjaxPages/AjaxCodes.aspx",
  dataType:"JSON",
  data:"userName="+$("#tbUserName").val()+"&flg=username",
  success:function(msg)
  {
  $("[id$=lbCheckUserName]").html(msg);
  }
  });
  });
   
  $("#tbPassword").bind("change",function(){
  var reg=/^[0-9]{6,}$/;
  var password=$("#tbPassword").val();
  if(password.match(reg)==null)
  {
  $("#lbCheckPassword").text("error");
  }
  else
  {
  $("#lbCheckPassword").text("OK");
  }
  });
});

asp 页面：
<%@ Page Language="C#" AutoEventWireup="true" CodeBehind="UserRegister.aspx.cs" Inherits="MyBookShop.UserPages.UserRegister" 
 MasterPageFile="~/MasterPages/index.Master"%>

<asp:Content ID="content2" runat="server" ContentPlaceHolderID="head">
<script type="text/javascript" src="../js/jquery-1.3.2-vsdoc2.js"></script>
<script type="text/javascript" src="../js/JCheckInfo.js"></script>


</asp:Content>

<asp:Content ID="content3" runat="server" ContentPlaceHolderID="ContentPlaceHolder1">
<table>
  <tr>
  <td>
  <asp:Label ID="Label1" runat="server" Text="用户名"></asp:Label>
  </td>
  <td>
  <input id="tbUserName" type="text" />
  </td>
  <td>
  <asp:Label ID="lbCheckUserName" runat="server" Text=""></asp:Label>
  </td>
  </tr> 
  <tr>
  <td>
  <asp:Label ID="Label3" runat="server" Text="密码"></asp:Label>
  </td>
  <td>
  <asp:TextBox ID="tbPassword" runat="server"></asp:TextBox>
  </td>
  <td>
  <asp:Label ID="lbCheckPassword" runat="server" Text=""></asp:Label>
  </td>
  </tr>
  <tr>
  <td>
  <asp:Label ID="Label5" runat="server" Text="确认密码"></asp:Label>
  </td>
  <td>
  <asp:TextBox ID="tbConfirmPassword" runat="server"></asp:TextBox>
  </td>
  <td>
  <asp:Label ID="lbCheckConfirmPassword" runat="server" Text=""></asp:Label>
  </td>
  </tr>  
  <tr>
  <td>
  <asp:Label ID="Label7" runat="server" Text="真实姓名"></asp:Label&g