Tomcat - Connection error from DataSource using JNDI

Hi, I'm trying to connect to an Oracle 8i database using JNDI lookup from Tomcat 4.1.30 and get an error I can't figure out.

The error message reads: org.apache.commons.dbcp.SQLNestedException: Cannot create JDBC driver of class '' for connect URL 'null'
This error seems to be when I try to get a connection from the DataSource object:
Connection conn = datasource.getConnection();

In attempts to figure this out, I created a test servlet that first connects to the database using the hard-coded driver and url, then JNDI.

The servlet doGet looks like this:
                  protected void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
            
            PrintWriter out = response.getWriter();
            String sDriver = "oracle.jdbc.driver.OracleDriver";
            String sURL = "jdbc:oracle:thin:@somecompany.com:1521:db1";
            try {
                  out.println("Attempting Oracle connection<br>");
                  Class.forName(sDriver).newInstance();
                  Connection conn = DriverManager.getConnection(sURL, "scott", "tiger");
                  conn.close();
                  out.println("Connected to Oracle okay<br>");
            
            } catch (InstantiationException e) {
                  out.println(e.getClass()+": "+e.getMessage()+"<br>");
            } catch (IllegalAccessException e) {
                  out.println(e.getClass()+": "+e.getMessage()+"<br>");
            } catch (ClassNotFoundException e) {
                  out.println(e.getClass()+": "+e.getMessage()+"<br>");
            } catch (SQLException e) {
                  out.println(e.getClass()+": "+e.getMessage()+"<br>");
            }
            
            InitialContext ctx;
            try {
                  out.println("Attempting JNDI connection<br>");
                  ctx = new InitialContext();
                  Context envctx = (Context) ctx.lookup("java:comp/env");
                  DataSource datasource = (DataSource) envctx.lookup("jdbc/operations");
                  Connection conn = datasource.getConnection();
                  conn.close();
                  out.println("Connected to JNDI okay<br>");
            }
            catch (NamingException e) {
                  out.println(e.getClass()+": "+e.getMessage()+"<br>");
            } catch (SQLException e) {
                  out.println(e.getClass()+": "+e.getMessage()+"<br>");
            }
            
      }

The output looks like this:
Attempting Oracle connection
Connected to Oracle okay
Attempting JNDI connection
class org.apache.commons.dbcp.SQLNestedException: Cannot create JDBC driver of class '' for connect URL 'null'

My server.xml looks like:
...
<GlobalNamingResources>
    <Environment name="simpleValue" override="true" type="java.lang.Integer" value="30"/>
     <Resource auth="Container" name="jdbc/operations" scope="Shareable" type="javax.sql.DataSource"/>
     <ResourceParams name="jdbc/operations">
        <parameter>
            <name>factory</name>
            <value>org.apache.commons.dbcp.BasicDataSourceFactory</value>
        </parameter>
        <parameter>
            <name>driverClassName</name>
            <value>oracle.jdbc.driver.OracleDriver</value>
        </parameter>
        <parameter>
            <name>url</name>
            <value>jdbc:oracle:thin:@somecompany.com:1521:db1</value>
        </parameter>
        <parameter>
            <name>username</name>
            <value>scott</value>
        </parameter>
        <parameter>
            <name>password</name>
            <value>tiger</value>
        </parameter>
        <parameter>
            <name>maxActive</name>
            <value>20</value>
        </parameter>
        <parameter>
            <name>maxIdle</name>
            <value>10</value>
        </parameter>
        <parameter>
            <name>maxWait</name>
            <value>5000</value>
        </parameter>
      </ResourceParams>

  </GlobalNamingResources>
...

My web.xml looks like:
<?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>
      <!-- define global vars -->
      
      
      <servlet>
     <servlet-name>TestServlet</servlet-name>
     <servlet-class>testJNDI.TestJNDI</servlet-class>
    </servlet>
   
      <servlet-mapping>
        <servlet-name>TestServlet</servlet-name>
        <url-pattern>/servlet/TestJNDI</url-pattern>
    </servlet-mapping>
      
      <session-config>
            <session-timeout>120<!-- in minutes --></session-timeout>
      </session-config>
      <resource-ref>
            <description>Oracle Datasource</description>
             <res-ref-name>jdbc/operations</res-ref-name>
            <res-type>javax.sql.DataSource</res-type>
            <res-auth>Container</res-auth>
</resource-ref>

      
</web-app>


Help!

Thanks in advance.