配置tomcat5.0连接池遇到的问题，请高人指点

我在使用tomcat5.0连接池功能时，得到的conn对象总是为空，真是郁闷，请高人指点。多谢多谢了！！！！

这是我的server.XML

<?xml version='1.0' encoding='utf-8'?>

<Server>

<Listener className="org.apache.catalina.mbeans.ServerLifecycleListener"/>

<Listener className="org.apache.catalina.mbeans.GlobalResourcesLifecycleListener"/>

<GlobalNamingResources>

<Environment name="simpleValue" type="Java.lang.Integer" value="30"/>

<Resource auth="Container" description="User database that can be updated and saved" name="UserDatabase" type="org.apache.catalina.UserDatabase"/>

<Resource name="jdbc/hello" type="javax.sql.DataSource"/>

<ResourceParams name="UserDatabase">

<parameter>

<name>factory</name>

<value>org.apache.catalina.users.MemoryUserDatabaseFactory</value>

</parameter>

<parameter>

<name>pathname</name>

<value>conf/tomcat-users.xml</value>

</parameter>

</ResourceParams>

<ResourceParams name="jdbc/hello">

<parameter>

<name>url</name>

<value>jdbc:Oracle:thin@127.0.0.1:1521:jingrui</value>

</parameter>

<parameter>

<name>passWord</name>

<value>tiger</value>

</parameter>

<parameter>

<name>maxActive</name>

<value>4</value>

</parameter>

<parameter>

<name>maxWait</name>

<value>5000</value>

</parameter>

<parameter>