Tomcat Connection pooling with oracle

[Chandrakanth]

hai
i want to use connection pooling in my application.
Now i use ordinairy database connections and that works fine.
I've configured a connection in the server.xml and added a resource-ref in
my web.xml.
but when i try to start my tomcat server,it won;t get started!!!!
any help greatly appreciated!!

Thanks & Regards
Chandrakanth