Hibernate + Weblogic + Classpath

I was trying out hibernate in weblogic server the other day.While developing my sample application I places all the required hibernate jar files in the application classpath( WEB-INF\lib\...) but I was unable to run the app till the moment I added them in the weblogic server classpath.

My Question is, why do I need to add those hibernate required jars in weblogic class path even when I have then within my application classpath. This reduces the protability of any app and actually forces me to configure servers before I deploy any such app?

Thanks
Sabyasachi

I put all the Hibernate (and related) jar files in my application classpath in Websphere. Works just fine. So you must have a Weblogic question here. Probably a solvable one, but "unable to run the app" doesn't give a mere mortal like me enough to work with.