Try saving the cart session bean's handle in your
JSP or
servlet session context. First time in, when you go to lookup the handle, it will be null, because you haven't saved one yet, so you find the home interface and do a create() and save the created bean's handle. Subsequently, all you have to do is get the bean from the handle.
The secret of how to be miserable is to constantly expect things are going to happen the way that they are "supposed" to happen.
You can have faith, which carries the understanding that you may be disappointed. Then there's being a willfully-blind idiot, which virtually guarantees it.