NullPointerException when initiating the connection pool

I have settings in the context.xml which contain the information for the connection of my database

<Context>
    <WatchedResource>WEB-INF/web.xml</WatchedResource>
    <WatchedResource>${catalina.base}/conf/web.xml</WatchedResource>

        <Resource 
        name="jdbc/*(my username)*" 
        factory="org.apache.tomcat.jdbc.pool.DataSourceFactory"
        auth="Container" 
        type="javax.sql.DataSource"
        removeAbandoned="true" 
        removeAbandonedTimeout="30" 
        maxACtive="100"
        maxIdle="30" 
        maxWait="10000" 
        username= *(my username)*
        password= *(my password)*
        driverClassName="com.ibm.db2.jcc.DB2Driver" 
        url="jdbc:db2://(my server host):50000/*(my username)*">
    </Resource>
</Context>

While for the Connection Pool I created a class to initiate and to connect it to the database. The error begins in the method of getConnection(). The way the error is NullPointerException in the return of the datasource.getConnection()

import java.sql.Connection;
import java.sql.SQLException;
import javax.naming.InitialContext;
import javax.naming.NamingException;
import javax.sql.DataSource;


public class ConnectionPool {
    private static ConnectionPool pool = null;
    private static DataSource dataSource = null;

    private ConnectionPool() {
        try {
            InitialContext ic = new InitialContext();
            dataSource = (DataSource) ic.lookup("java:/comp/env/jdbc/COMPANY");
            System.out.print(dataSource);
        } catch (NamingException e) {
            System.out.println(e);
        }
    }

    public static synchronized ConnectionPool getInstance() {
        if (pool == null) {
            pool = new ConnectionPool();
        }
        return pool;
    }

    public Connection getConnection() {
        try {
            return dataSource.getConnection();
        } catch (SQLException e) {
            System.out.println(e);
            return null;
        }
    }

    public void freeConnection(Connection c) {
        try {
            c.close();
        } catch (SQLException e) {
            System.out.println(e);
        }
    }
}

I tested the database connection with Eclipse's Perspective Database Development and I was able to connect and done all the queries.

In addition, it gives me this error in output

SEVERE: Unable to create initial connections of pool.
java.sql.SQLException: No suitable driver found for jdbc:db2://db2.cecsresearch.org:50000/(my username)

Although I have the jar library files in the lib folder and in the classpath.