Java Database Connectivity (JDBC)

Hello,

I have trouble to make run an web app, running with tomcat 4.1.29, hibernate connecting to oracle9i.
Everything is working well when I use classes12.jar (driver for oracle 8i) and when I connect to a oracle 9i database.

But i get the following error when I work with classes12.jar (driver for oracle9i) or ojdbc14.jar

Here is the java error in tomcat console :

Caused by: java.lang.NullPointerException
	at org.apache.commons.dbcp.DelegatingConnection.close(DelegatingConnection.java:151)
	at org.apache.commons.dbcp.PoolableConnection.reallyClose(PoolableConnection.java:95)
	at org.apache.commons.dbcp.PoolableConnectionFactory.destroyObject(PoolableConnectionFactory.java:301)
	at org.apache.commons.dbcp.BasicDataSource.validateConnectionFactory(BasicDataSource.java:883)
	at org.apache.commons.dbcp.BasicDataSource.createDataSource(BasicDataSource.java:851)
	at org.apache.commons.dbcp.BasicDataSource.getConnection(BasicDataSource.java:540)
	at org.hibernate.connection.DatasourceConnectionProvider.getConnection(DatasourceConnectionProvider.java:69)
	at org.hibernate.cfg.SettingsFactory.buildSettings(SettingsFactory.java:72)
	at org.hibernate.cfg.Configuration.buildSettings(Configuration.java:1823)
	at org.hibernate.cfg.Configuration.buildSessionFactory(Configuration.java:1143)
	at com.snecma.ecom.ecm.orm.HibernateUtil.<clinit>(HibernateUtil.java:26)

Here is tomcat config : server.xml

		<Resource name="jdbc/myoracle" auth="Container"
		              type="javax.sql.DataSource"/> 
		<ResourceParams name="jdbc/myoracle">
		  <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:db_user_name@192.0.0.1:1521:DB_INSTANCE_NAME</value>
		  </parameter>
		  <parameter>
		    <name>username</name>
		    <value>db_user_name</value>
		  </parameter>
		  <parameter>
		    <name>password</name>
		    <value>db_user_pwd</value>
		  </parameter>
		  <parameter>
		    <name>maxActive</name>
		    <value>20</value>
		  </parameter>
		  <parameter>
		    <name>maxIdle</name>
		    <value>10</value>
		  </parameter>
		  <parameter>
		    <name>maxWait</name>
		    <value>-1</value>
		  </parameter>

Here is my hibernate config file :
hibernate.cfg.xml

<hibernate-configuration>
    <session-factory name="seessionFacName>
        <property name="connection.datasource">java:comp/env/jdbc/myoracle</property>
        <property name="hibernate.dialect">org.hibernate.dialect.Oracle9Dialect</property>
		<property name="show_sql">false</property>
		<!-- Uncomment for runtime -->
		<!-- Comment for build -->
	 	<mapping resource="app.hbm.xml"/>
	 	
    </session-factory>
</hibernate-configuration>

Do you have any clue to solve this problem ?
Thanks