Thanks for ur suggestion
The problem is with the configuration element in server.xml
With tomcat 5.5 we should use
<Resource name="jdbc/myoracle" auth="Container"
type="javax.sql.DataSource" driverClassName="oracle.jdbc.OracleDriver"
url="jdbc
racle:thin:@localhost:1521
racle"
username="scott" password="tiger" maxActive="4" maxIdle="2"
maxWait="10"/>