连接池问题，高手们快帮我看看，谢谢！（tomcat5.5.23）

javax.servlet.ServletException: Name jdbc is not bound in this Context
上传到空间后，没有办法修改tmcat_home下的server.xml文件，所以在我自己目录下增加META-INF/context.xml文件，和WEB-INF/web.xml来配置。
Context.xml
<?xml version="1.0" encoding="GBK"?>

<!--Context path="/" docBase="" debug="5" reloadable="true" crossContext="true"-->
<Context>
<Resource
auth="Container"
description="test"
name="jdbc/connectDB"
type="javax.sql.DataSource"
driverClassName="com.microsoft.jdbc.sqlserver.SQLServerDriver"
maxIdle="2"
maxWait="5000"
username="sa"
password="pwd"
url="jdbc:microsoft:sqlserver://(主机IP):1433;DatabaseName=db"
maxActive="4"/>
</Context>

Web.xml
<?xml version="1.0" encoding="ISO-8859-1"?>

<!DOCTYPE web-app
PUBLIC "-//Sun Microsystems, Inc.//DTD Web Application 2.3//EN"
"http://java.sun.com/dtd/web-app_2_3.dtd">

<web-app xmlns="http://java.sun.com/xml/ns/j2ee"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://java.sun.com/xml/ns/j2ee
http://java.sun.com/xml/ns/j2ee/web-app_2_4.xsd" version="2.4">

<description>
Welcome to Tomcat
</description>
<resource-ref>
<description>connectDB</description>
<res-ref-name>jdbc/connectDB</res-ref-name>
<res-type>javax.sql.DataSource</res-type>
<res-auth>Container</res-auth>

</resource-ref>
<servlet>
<servlet-name>regservlet</servlet-name>
<display-name>regservlet</display-name>
<description>regservlet</description>
<servlet-class>cn.regservlet</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>regservlet</servlet-name>
<url-pattern>/servlet/regservlet</url-pattern>
</servlet-mapping>
</web-app>

测试JSP文件
<%@ page contentType="text/html;charset=gb2312"%>
<%@ page import="java.sql.*"%>
<%@ page import="javax.naming.*"%>
<html >
<body >
<%
Context initctx = new InitialContext();
javax.sql.DataSource ds = (javax.sql.DataSource)initctx.lookup("java:comp/env/jdbc/connectDB");
Connection conn = ds.getConnection();
Statement stmt=conn.createStatement();
String sql="select * from AdminInfo";
ResultSet rs=stmt.executeQuery(sql);
while(rs.next()) {%>
您的第一个字段内容为：<%=rs.getString(1)%>
您的第二个字段内容为：<%=rs.getString(2)%>
out.print("数据库操作成功，恭喜你");
<%}
rs.close();
stmt.close();
conn.close();
%>
</body >
</html >
运行JSP文件，出错。